Back when I was an acoustician, I had gear that ran on CPM.

I still run into stuff running CP/M as a friend offering "bail me out, pal" advice to people I know. It is light weight, low latency, solid as software can be, and loves to have analog data fed into it via serial ports. Novell supposedly has some of the similar benefits, but I never got into the Novell stuff.

From my own experience, USB to Serial conversions work for people who do not need microsecond or better timing. I use a few of these adapters to feed GPS time signals into cameras for a telescope and spectroscopy project I gave up on a few years back. I did not have an old PC that could run WinXP reliably, so I had to use Windows 7 and the converters. Since you are an audio guy, you've probably run into this as well.

This same issue is one of several reasons why the 'real' stuff uses Audrino and not Raspberry Pi for their inputs. Microsats for instance. It is my understanding that the Pi inputs run over USB while the Audrino run native into the bus.