Basically what happened is one "security researcher" who wasn't that good at the "research" part of his job upgraded a system to Vista and had audio issues. He then wrote a blog piece about how Vista sucked and theorized that it was DRM causing issues. This got echo-chambered over the Internet tons and because "Vista's DRM won't let you have good audio."
It amused me since, when I read it, I had Cakewalk Sonar loaded in the background and was working with pro audio at the time, in Vista, no issues at all.
What had really happened is his system had a old, low end, integrated soundcard. The manufacturer provided poor quality Vista drivers that didn't work well in full duplex (recording and playing back) mode. So if you were using the mic and output, sound quality was degraded. This was a function of the sound chip and its drivers, not Vista. It was, and is, fully capable of doing 24-bit 192kHz or greater multi-channel audio in and out, as are subsequent versions of Windows.
The DRM that showed up in Vista related to audio is "protected audio path" and is only relevant to shit like Blu-ray playback. The media industry won't give out licenses to AACS and BD-J unless the whole setup it DRM'd including the drivers. So Vista added this capability (and subsequent Windows versions keep it). A program can say "I am playing DRM'd content, you need to protect this" and the driver will then make sure that screenshots/recording can't happen, that it only plays on HDCP enabled outputs and shit like that. However normally all that is turned off and it affects nothing if you don't use it. While it is silly, it was either implement it, or Windows would never be able to (legally) play Blu-rays.