Re: Why did Sennheiser [..] do this nonsense?
My question exactly. I've had radio headphones plugged into the TV for years, they didn't need no stinkin' app to work.
My current headphones are a not-too-pricey Sony model that work fine and plug in like every other kind I've ever had. I fail to see what is the point in having an app at all. You have an app for the sound card (or chip these days), that is where the tweaking should take place.
But headphones are for listening to the output, not for fiddling with it.