Russ, your internal Real Tec will work just fine for what you want. The semi-pro or pro geeks among us are correct in that an interface is certainly better but lots of folks are using their internal chip with Biab. That will work fine until...

You want to record audio into your computer. That's why you got the mixer. But the problem is as RHarv said, the internal soundcard and the mixer are both audio devices. So, if you want to still use that mixer then you have to select the mixer as your sound device. That will disable the Real Tec which means no midi but I think you would still hear the RT's. Once you have your audio recording in Biab you could switch back to the Real Tec and it should work.

What most guys do who are keeping things simple is to not use a mixer, they'll simply get an adapter and record direct into the line in on the MOBO. The quality will be questionable but you might not notice. When folks say the overall quality of an external interface is so much better many times in the real world, listening on your home sound system, you can't tell the difference.

As far as your problems with your Win 7 install, you did the same thing I did. We both went cheap and didn't want to purchase the physical Win 7 install disc for $160 or whatever it was, we simply bought a PC with an OEM install. What you should have done is create a recovery disc first thing and put it in a drawer. I don't think you did that and neither did I. I'm not sure but I don't think somebody else's recovery disc will work because it's off of their system and authorization. As you said, Win 7 is no longer available unless you happen to find an unused disc on Ebay or something.

A computer repair shop could probably either clean up the problem without reinstalling or reinstall Win 7 but it'll cost you, probably about the same as if you had bought the original disc in the first place. You can call the Geek Squad at a Best Buy and ask what they would charge.

As far as Win 10, it's certainly different looking but under the hood it's still Windows. My sister has a Win 10 laptop and I played with it enough to figure that much out. It's Windows and works fine.

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.