Selling a Macintosh Amplier MC-352

My audiophile husband died last year. Now the audio system he lovingly crafted and tweaked over a number of years is in the hands of a terrible mother who has no idea what to do with it. He'd be horrified, but I just want something simple to use that I can control via my computer. He was an enthusiastic user of Audiogon, so I'm coming to those of you in "The Club" with the hope that you can help me figure out what to keep and what to pass along to someone who will appreciate it better than I can.

My first question is about the amp and preamp. The amp is a Macintosh MC-352. The preamp is a Macintosh C2200 Tube Preamp. (He also has a Macintosh MCD 205 compact disk changer, but my question is really about the amps.)  Sonos tells me that I can plug my turntable WITH a preamp into the Sonos device. (The CAPS are mine, for emphasis.) What I don't understand is whether this means I can use the preamp I have, or if I have to have a turntable that has a built-in preamp (not even sure if there is such a thing). Do I need to keep my preamp?

The second question is about the amp MC-352. I notice that there are none for sale on Audiogone. I don't know if that's because there's no real market for them, or if it's simply rare to see them for sale. I do find a price in the Bluebook for them.  So, is there a market for the MC-352?

Can any of you help?

Elise