Why did this just happen ?

Since I'm not an Apple anything fan....

If you're using a pc, m/bs' for gaming will help since the concept is speed at all costs....this includes audio as well as video.

Apply the best soundcard you can rationally afford, as audio 'cues' in games can mean the difference in 'game life v. death'.  Comments from players about 'hearing something from Behind You' early enough to respond to avoid having you butt handed to you....

Max your RAM with the fastest you can find for the m/b and processor...'garbage in = garbage out' still applies...

Look....the bulk of pcs' and macstuff is aimed at the 'average abuser'.

Bite the process and Build a 'puter that will do what You want it to.

You can still use your DAC....although that process happens in your laptop daily.

(...I'm in a rare PO'd state, and tired of 'hearing' "...I spent XK$ on a DAC/streamer/magic box that I'm disappointed with..." which has the basically the same innards as a 'built puter' for more or less the same outlay....

For 'techno types' as most seem to aspire to or claim...

...y'all are disappointing....

...and y'all can start flinging dog waste at me now....

@wturkey ....you're excused from the previous....

At least, you asked....👍

I think it’s the sampling rate, dropped bits, or elimination of noise on the USB. PCM uses packets to wrap up and send information. If it runs out of time, it drops bits. The cost is resolution. Computers are getting better and better at this. It’s why I went to DSD back in the day. 
 

Full disclosure - I’m an analog guy. I do use a PC for my digital (the horror) but I do not stream. Everything I listen to I have spent the past 25 years recording and cataloging myself from analog sources. For how I use it, it’s fine for me. Say what you want to say about PC/Mac as a source, I don’t have enough years left on this planet to redo that work. You didn’t say if you were streaming or playing from your drive. If you’re going to consider a streamer and you have cataloged your songs, I would look very hard at the interface and how it could hold onto that information. 
 

Regardless, this sounds like a good problem to have. Congrats and enjoy. 

Less noise

You didn’t specify which MacBook Pro you are now using. If it is one with the M1 processor, that is part of the answer, plus better/faster processing from the ram, storage, and input and output. Beyond that, results will vary depending on what else is connected to the Mac, and what other software is running. Changing the USB output cable to accommodate the USB C likely also contributed some to the change. Speaking from some experience going from an old Mac Mini 2011 to a new M2 Mac Mini 2023. Even with the newer processor which stepped sound quality up, a new better USB cable also made a difference.