back to article Arcam rPac

Arcam’s rPac is a digital-to-analogue converter (DAC) and headphone amp designed for anyone who listens to music on a computer. Or, more accurately, anyone who does so and cares about audio quality. Arcam rPac Relying on the computer to perform the digital to analogue conversion usually results in noisy tracks and jitter, …

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The difference is clear?

Did you do a double-blind test? If you knew which device you were listening to, the difference is just as likely to be imagined as clear. Does anyone take this sort of article seriously any more?

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Re: The difference is clear?

Sigh, yes. Yet-another audiophile article that ignores quite a lot of science and just asserts something is better because they think it is (and, worse, worth that amount of money to get).

Do a proper double-blind. It literally takes two assistants, a couple of other "convertors" (e.g. laptops / desktops with sound cards that I imagine The Reg has a bucket load of lying around) over and above what you needed to review the product in the first place. It's simple to do. It's HARD to disprove if you consistently pick out one source as the "better sounding", especially if your assistant is an audio engineer with a frequency-analyser tasked with matching all the levels and making sure one's no more bassy or trebly than the other by using only the settings available on the machine producing the sound.

If he can make the sound of a cheap laptop sound "better" to you than this device, this device is worthless and you'd be better off paying him to adjust your cheap laptop instead to get a better sound. If he can't, then this device probably is "worth" having (depending on whether you think £150 for a slightly better DAC is actually worth anything at all).

Seriously, even the most Heath-Robinson of tests would have been SOMETHING. Get the guy sitting opposite you to string the cabling out of the room and then STAY OUT of the room and swap between devices at random (completely at random, roll a dice or something), while recording which ones he swapped in what order. Then have someone in the room with you (who CAN'T see the apparatus and DOESN'T know what order your assistant is plugging them in) to record whether it was device A, B, C or D (that's the only info the plug-swapper can give, ideally by some non-vocal communication like holding up a card or pressing a button) and what you think of it. Only at the end does ANYONE except the guy plugging them in tell you what A, B, C and D actually WERE, and you will NEVER have heard which letter was plugged in at any point.

Over and above average review time? Probably five-ten minutes of explanation and a couple of family members, friends, colleagues, etc. Amount of value added to the review: Some. (i.e. at the moment, there is no value. This would at least add some value, so infinitely times the amount of value currently there).

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Re: The difference is clear?

I've had some some PCs with appalling sound output (I could hear the mouse cursor moving!) so a blind test wouldn't help us readers much unless we had the same computer as the reviewer. YMMV etc

How does it compare to similarly priced - and far more versatile - external sound cards?

Seems you might be better off with a second-hand iRiver H120 with Rockbox if music is your thing.

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Anonymous Coward

Re: The difference is clear?

It's always a few factoids, followed by, 'sounded great' well worth the money'. Can't seem to recall a Reg audio review that went along unfavourable lines -

'The Wibwab Smegmatron is an external USB DAC. Sadly, on comparing it the the sound from my laptop, on tracks like Bust my Nads by The Flaming Fartpants, it sounded muddier than a 1980-vintage Walkman with flat batteries. Avoid at all cost and spend the £250 on beer instead'.

As other commentards forcefully replied to my past whinges about these lightweight subjective reviews, 'this is not an audiophile website'. Strangely though, the Reg manages to do objective and informative reviews of cameras.

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Re: The difference is clear?

More hilarious: I looked up the chip that it makes a big fuss of on the article and got this from an AUDIOPHILE website:

"This is TIs attempt at producing an inexpensive DAC that requires an extremely small number of supporting components and only requires a single 3.3v PSU from which to work... If you're expecting class leading THD/SNR and digital filtering then you are not appreciating what this device is supposed to be used for, it isn't intended as a top line audiophile product. "

And, yes, from the datasheets it appears to be a fairly cheap (sub-£10), fairly ordinary audio DAC.

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Re: The difference is clear?

I did exactly the same and saw a THD of -93dB, which isn't even 16 bit! £3 worth of DAC for £150? I bet it doesn't do DTS or AC3 either but is plain PCM so not much use for watching movies. And a cheap'n' nasty digital volume control can only lose bits on the way so giving even poorer THD.

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Informative reviews of cameras

I guess that's partly because for a camera they have to provide sample images for all to assess, and there is also a lot more to cameras which can at least be discussed semi-objectively, such as features, ergonomics and battery life.

It's clear that this article was simply another puff-piece to sell a pointless overpriced gadget to the gullible via a referral link. The rating of "90%" is probably calculated automatically from the amount of commission.

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Re: The difference is clear?

How can a volume control "lose bits on the way"? It will act on the output buffer and be analogue only, having no affect on the bits.

Anyway, there are so many problems with this DAC it beggars belief.

It uses the PC 5v bus, produced from a noisy SMPS, with a hopeless grounding technique that will only inject noise.

The article states jitter free, but in all likeliness the opposite is true, the DAC must be using an external clock and without a clock-lock method will inherently produce jitter.

And like others have mentioned, it's a pretty cheap IC with far from amazing specs. Most sound cards I have come across have had pretty good onboard DACs and analogue outputs, that at most require a nice little external analogue buffer circuit, especially for those hard to drive headphones.

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Are you sure

..that Butt House Blondes is anything whatsoever to do with music and not some grumble flick?

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Alternative

How does this compare with, say, the Soundblaster X-Fi USB which has considerably more features, 5.1 surround capability and costs less than half the price?

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You don't understand

It's not "a solid block of aluminium". Nor does it cost £150. Therefore it doesn't sound as good.

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Re: Alternative

How dare you compare this with a sound card, when it has only half the functionality?

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Oh my, Reg you have dropped the ball here.

I read your review and thought, What the...... well lets not go there. So I saw that nobody had commented on this article so I thought I would get the ball rolling, however loads of people have and they are all right. This is an attempt to get the stupid to buy a product to improve the quality of an algorithm??? think about your readers...... or did you? looking back at this article its quite funny that these products exists. So lets remember readers this product really do exist and fools will enjoy it and brag to their friends. Now thats worth talking about.

p.s. fix your web page

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But...

You could get an M-Audio Fast Track 2 for less money, or a Fast Track Pro for the same money and have a shitload of extra functionality. And it would probably sound better. If you could notice the difference.

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Would you like to buy a bridge?

Those DACs cost under $3 in volume, they have on-board USB and sp/dif, and they can drive headphones directly. You need about another $1 of discrete components to make something that goes all the way from the USB in to the headphone socket out. You can get away with cheapo components since the whole point of that DAC is that it does the full job and is robust against interference and jitter.

Let's be generous and say $5 for the electronics. Care to explain where the rest of that £150 comes from? Pure voodoo.

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Re: Would you like to buy a bridge?

I have pretty good idea where the costs are, and I doubt brand premium exceeds halve of price (although I still would not be happy to pay it).

You may want to follow http://nwavguy.blogspot.co.uk/ to gain some insight on how these things are designed and costs involved.

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Re: Would you like to buy a bridge?

Rather than spamming a blog, perhaps you could simply explain what else you believe is inside that pretty box that would bring the necessary BoM and design costs into double figures, let alone up to £75 or £150.

I just poked around and the same (or essentially the same) DAC is used in several of those cheapo USB-driven (rather than USB-powered) PC speakers. So that's the entire useful contents of that box plus two (or four) drivers, power/volume control, caseworks, headphone output and cable to connect the satellite speaker ... all for between £25 and £50 retail.

So ... can you persuade me that this device is anything other than audiophile homeopathy?

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Mushroom

Re: Would you like to buy a bridge?

"To anyone suggesting all DACs etc sound broadly the same I suggest you read up and understand the required overall architecture before opening your mouths and going off half cock"

with apologies to John Dawson, below.

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Re: Would you like to buy a bridge?

That's not what I asked.

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Black Helicopters

Don't be too harsh

it is easy to plug in and works.

If you can get a £10 box of bits and sell it for £150, welcome to capitalism.

A lot of cheap laptops have crap sound out, and this will fix it, but for £150 extra you could get a laptop with decent sound out. I think the M-Audio products are very good

A lot of second hand DACs available very cheaply though.

I bought an old meridian DAC second hand off the bay which I feed from my MBP's optical out, and an adaptor and the whole thing cost me £100, including a tinfoil hat.

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Re: Don't be too harsh

A lot of laptops do indeed have crap sound out but if this fixes it then so will a $5 USB "sound card" imported from Hong Kong. They too are easy to plug in, and work.

In my experience, the main problem with laptop analogue outputs, when fed to an external amplifier, is earth loops. The heavy varying current flowing through the negative wire of the laptop's long power supply cable causes its local earth, and hence its audio output, to move up and down compared with the connection to true earth at the power supply of the laptop (if it is earthed). If you connect the laptop to an earthed amplifier it will see this variation superimposed on the audio (as well as carrying some of the earth current) and you will get nasty buzzing noises varying with computer load.

The safe way round this is isolation (digital output via opto-isolator or fibre, audio transformer, run the laptop off batteries or use a double-insulated amplifier) or using an amplifier with a balanced input, which will be referenced to the laptop's earth rather than true earth. Engineering, rather than snake oil involving solid aluminium blocks.

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Re: Don't be too harsh

"If you can get a £10 box of bits and sell it for £150, welcome to capitalism"

Absolutely. But when somebody does sell a £10 box of bits for £150 it is the responsibility of people who know better to point that out. And a reviewer on a techie website should be one of the people who knows better. Writing a fluff piece that gives that £10 box of bits a score of 90% is weak.

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Re: Don't be too harsh

Laptops have no connection to earth as they are isolated, GND is not connected to earth in any way, if you don't believe me, crack open a laptop PSU and check. Besides, any decent amplifier should have a star ground topology to prevent earth loops feeding back through the power supply.

Digital outputs and fibre have their own inherent problems requiring perfectly matching clocks either side.

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WTF?

It doesn't even have gold plated connectors!

You know, the sort which the monobrow sub-estate-agent pond-dweller in electronics retail outlet of your choice describes as "...only letting the clean electrons through." (I kid you not). There ain't arf a lot of toss spouted about hifi. £150 for an isolated DAC, c'mon? Laff, having you most certainly are. Could buy 3 really nice (I mean REALLY nice) dedicated media devices for this wad.

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Re: It doesn't even have gold plated connectors!

oh my, and this one http://epiphany-acoustics.co.uk/our-products/ehp-o2d-miniature-desktop-headphone-amplifier-with-usb-dac/ is even more expensive. And that's not even half of the scale if you are into audiophile equipment.

I guess if you use iShite ear buds then it does not matter, but for someone who prefers to listen to music instead of electronic noise, it matters. These few hundred quids (half on DAC + phone amplifier, half on headphones or earphones) aren't really that much to pay compared to audiophile setups.

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So?

"These few hundred quids (half on DAC + phone amplifier, half on headphones or earphones) aren't really that much to pay compared to audiophile setups."

True, but your point is? All that statement says is that there are even more expensive things you can buy. Nothing about whether they offer any better sound quality. And you will never find a double-blind test of any of them because everybody knows they don't.

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Re: So?

Oh I will not comment on whether these very expensive setups are worth the price; frankly I don't quite believe it.

I only comment on quality difference when you start with "equipment" at floor level of few quid!

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I need a new soundcard (Balanced outputs (speakers take balanced TRS or 1/4" mono jack - (Can take unbalanced but doesn't seem to work very well like that)) / separate channel for headphones).

Dunno what to get but I know it is not this

Any advise (Rather have internal or just the dac external)

Not stupid expensive (Tapco USB I have is getting old bad contacts for speaker cable - No proper W7 drivers either). Don't need any fancy stuff just simple solid drivers.

Only want it to sound half reasonable for listening to music. (Don't really make any music anymore - sometimes play with dj mixing program (Pretty rarely))

(Linux support desired but not essential).

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Anonymous Coward

Look for something called (no this isn't a typo) Juli@. Might be made by ESI, but my brain cells a rusty. It is a sound card respected by the few music lovers who aren't audiophiles demanding machined-aluminium cases and all that stuff (not that looks don't count, they do).

For you: it is configurable as balanced i/o or unbalanced i/o.

I haven't heard it, just good reports about it.

I use a Echo Audiofire2. It has balanced i/o. It also requires Firewire. Firewire-audio + Linux = Nightmare. If you do ever find yourself fighting jackd "overruns" when all you want to do is listen to music, check out something called KXStudio.

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Only advice I can give is...

... be careful of Firewire-connected sound cards on PCs- some soundcards will only work if your FireWire chip is made by TI. [Standards! : D]

But I'll imagine you probably go for USB.

(I still can't work out what Win7 is doing to my audio out, and which mixer takes precedence over another. It seems that none of the volume controls in individual programs covers the whole range... confusing)

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Anonymous Coward

That's good advice!

Which I forgot. It is, I think, specified for the Echo Audiofire range.

Any interface should be checked out by google etc for Linux support before buying, but this is especially true of Firewire. If I had known anything about it before buying the unit, I would never have gone with the Linux/Firewire combination.

www.linuxmusicians.com is useful. They even have a wikki of interfaces found to work.

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Anonymous Coward

But it reproduced whalesong perfectly!

This must truly be an amazing device: it has such purity of reproduction, I could hear the whalesong from the review all the way from Kansas!

But it cannot be any good - it doesn't have Genuine Oxygen Free Copper, nor 24k Gold plating, nor Extra-Virgin Yak Wool insulation, nor $5k/ft sooper-grade USB cables, nor a harmonic-neutralizing rock pad to sit on, nor was it properly "trained" by 20 hours of Tibetan Throat-singing monks! And not a single fire-bottle in sight! - don't you know you simply MUST have tubes in the outputs!

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Aha.

I say Arcam makes a nice profit on this one. They'd wax more about the headphone amp's output stage if it was really worth anything. Def. not £150 nice. I would spend $(sic)150 on something just like this made by some good folks in Bozeman, knowing very well about it being entry level. For $250, you should be doing much, much better than "crap chip, digital volume, very limited power supply"

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Stop

I've never come across a motherboard that had anything better than dreadful line out capabilities, so I don't have any particular problem with the reviewer's "the difference is clear" remark. It would have to be a truly awful piece of kit not to make a "clear" difference. All this piss and vinegar about double blind testing is, in this case at least, a total red herring. You don't need double blind testing to tell the difference between a penny whistle and a church organ, and you don't need it to tell the difference between mobo and external DACs. Not that the DAC in your mobo is particularly crap, it just suffers from the most hideous RF interference it's possible to find anywhere in your home. This affects the analogue output more than it does the actual D-A conversion - in that respect the wording at the beginning of the review is inaccurate.

However if you're going to go to the effort of using your rig for hi-fi listening purposes (as opposed to studio use) you're much better off investing in a 2nd hand S/PDIF compatible DAC with balanced outputs and using it to drive a cheap set of studio monitors.

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But companies like FiiO make much more fully featured headphone amp/DACs than this for less money. I bought an E7 because I have sensitive IEMs and my work PC output is too noisy.

Don't be silly about ABXing, The Reg are just another What Hi-Fi? when it comes to audio reviews, i.e. to be avoided and ignored ;)

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Well I have I an Acoustics degree and a £5K HiFi. I don't have a rpac but I have the rdac and several pc soundcards. As the sound is essentially very similar between them all it is difficult to categorise how much an improvement is worth when switching between them.

However a more solid sound with more punch when the music needs it and more control when the dac needs to pull the sound back. Airy silence around the thumps and the strums and the energy going towards the notes the system is trying to reproduce rather than all over. A more natural pleasing sound to the vocals that conveys more emotion and subtlety. A better organised sound with a more correct timing between sampling points making it easier for the brain to process. All these things are worth hundreds upon hundreds to me. It takes sitting back and relaxing for me to sense whether I value a product in my system or not over hours, days or weeks.

I have bought wires costing more than the rpac per metre to connect my kit and I can't hear the difference. With a good dac chip surrounded by good analogue components:- a good power supply section, a good low level amplification section, separation from interference ridden pc components and biased to my tastes though and omg it is worth the money.

...but its all about how much the dac chip costs and how many features and the SN ratio isn't it...

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Boffin

jitter-free analogue signal

Jitter is a digital thing.

If the reviewer thinks that this box is jitter-free, I'd like them to tell us what jitter sounds like. If they can do that, I might believe that they know what they are talking about.

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Re: jitter-free analogue signal

Jitter is indeed about small timing errors in digital signals, below the amount needed to cause real bit-errors.

This would not normally matter except that in digital audio it is necessary to have a really clean clock at the audio DAC (or ADC); otherwise errors in the timing are equivalent to linearity errors in output level from one bit number to the next.

The problem with digital audio interfaces (S/PDIF, HDMI and USB for example) is that no clean master audio clock is actually transmitted over the interface - you have to reconstruct it at the receiving end. This is not as easy as it sounds. One way is to use a FIFO and clock out using a clean clock and ask the transmitter to vary its rate so as to avoid overflow/underflow. This is impossible with S/PDIF as it is one way but is possible with USB provided you use the method. There is not much silicon around that actually does this - Arcam is one of the few companies to implement it in all its USB DACs right down to this inexpensive one. The other solutions use the 1millisecond frame rate associated with USB and this produces a LOT of timing errors i.e. jitter which modulates the audio output signal.

As to what it sounds like - well that depends on both the amount and frequency spectrum of the jitter. Where it is intrusive it can be likened to looking at a scene through a dirty window - when you clean it (remove the jitter) the whole picture cleans up too.

HTH - it is intended as a serious answer.

John Dawson

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Meh

Re: jitter-free analogue signal

"Arcam is one of the few companies to implement it in all its USB DACs right down to this inexpensive one."

The USB stack is built into the TI DAC. The only other digital i/f into the DAC is s/pdif. How are Arcam implementing anything novel in the USB connection in this product?

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FAIL

Re: jitter-free analogue signal

Umm... to which TI DAC are you referring? It is certainly not the PCM5102. Perhaps you are thinking of the PCM270x family? These parts are limited to 16 bits 48ks/s and have a crude clock recovery system that produces LOTS of jitter related products in the audio output. They are fine for simple USB speakers etc but are not hi-fi in the highest quality sense of the word.

Please read my main posts in this thread to find out more.

John Dawson

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Meh

Re: jitter-free analogue signal

Apologies. You're quite right. The datasheets I was looking at were packages with both the DAC and a TI USB controller. The PCM5102 itself doesn't have on-board USB.

It's interesting that your main post mentions your abundance of gear (or 'ear') to test this on and yet neither the TI sales bumph nor this review contains any objective testing.

No offence, but until somebody actually posts something material rather than these empty assertions then I'm sticking firmly with my original audiophile voodoo assessment.

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Re: jitter-free analogue signal

(that should be "Arcam sales bumph")

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Facepalm

It's a USB powered DAC implemented with asynchronous transfer protocol...

...and it's aimed mostly at laptop users, so it needs low power consumption. Nevertheless you get something with around 110dB signal to noise ratio which is capable of driving headphones of any impedance to a decent sound level without audible distortion or noise. There's even a handy volume control on the box to save faffing about with a mouse. You don't get all this from any computer motherboard or laptop I know of. Sure some premium sound cards might perform as well (and quite possibly even better) but that's not what this product is competing with.

What we observed is just how many people store their music libraries on a laptop or PC, spend lots of money on headphones (I am talking hundreds of pounds) and yet don't have decent electronics to drive those headphones. To do this well for 150UKP retail is actually pretty impressive imho.

And not one of you referred to the method of ensuring proper clock recovery so that the chosen DAC chip can work to its full potential over USB. I promise you it makes a BIG difference to sound quality when sending audio over USB. It's also expensive to implement - there's a fancy XMOS processor in the box..To anyone suggesting all DACs etc sound broadly the same I suggest you read up and understand the required overall architecture before opening your mouths and going off half cock. I have given lectures and workshops to the AES on this topic.

My admission here - I was involved in the architecture of the rPAC and I am a bloody good audio electronics engineer with a deep understanding of the difficulties of analogue and mixed signal design. I also have 30Ks worth of my own ear to measure this stuff properly. On the other hand I didn't write the marketing blurb or have anything to do with the reviewing process.

Hey if you like music and have decent headphones why not try an rPAC? If you purchase it mail order you can no doubt demand your money back in 7 days if it doesn't do what it says on the tin. It won't take that long to find out ;)

John Dawson

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Anonymous Coward

Actually....

I think that a lot of the stick is about the review, rather than the product.

Whilst I think that the standalone DAC is the most oversold item in hifi, I have nothing against this one. Another thing that nobody mentioned is that Arcam has been a respected name in hifi for a long time. I honestly would not expect them to produce rubbish. What's more, they are respected in down-to-earth hifi rather than silly-money hifi.

As to cost, size and convenience, it probably compares with my Echo Audiofire unit, but it is true to say that that does twice as much (input as well as output). This is part of the marketing genius of the hifi manufacturing world, and I am cynical enough to think that someone, somewhere, thought, "Hey! Let's produce something with half the functionality at twice the price. Winner!" I'd like to think that, by spending the money on less, you get better. This is why I have an interface that does not sprout mic inputs and preamps that I wouldn't use.

Motherboards now have built-in "soundcards" that are infinitely better than those of a few years ago, but, if I wanted something that might be better yet, and was able to rule out wanting to record, would I consider this device? Certainly, I would.

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Anonymous Coward

Oh, and...

The first poster did hit nail on head with the point about [double-]blind testing.

The refusal of the industry and its publishing bedfellows, on and offline, to take this fully onboard is a disgrace. The fact that it is endorsed by big-spending customers, who actually wish to be seen as over and above all that sort of thing, is successful con of religious proportions.

"As far as the real world is concerned, high-end audio lost its credibility during the 1980s, when it flatly refused to submit to the kind of basic honesty controls (double-blind testing, for example) that had legitimized every other serious scientific endeavor since Pascal. "

--- J. Gordon Holt, founding editor of Stereophile.

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Re: It's a USB powered DAC implemented with asynchronous transfer protocol...

Heh - one obvious typo - ear should of course be gear - oops!

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Re: It's a USB powered DAC implemented with asynchronous transfer protocol...

I did spot that typo, and it almost made some kind of sense - one would test hi-fi with an ear (mono, obviously!)

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Re: Oh, and...

I'm more in line with Noel Keywood's opinion on double blind testing. It's not the panacea so many people make it out to be.

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Anonymous Coward

It is not intended to be a panacea

It is intended to ensure basic honesty and to protect against total bullshit.

Now, I have some crystals you might like to buy: It doesn't matter where you put them, they will make your hifi sound better, your car go faster, and your lovelife better...

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