Technics 1200 MK3D

I would say no to using the MIXER in any respect. Instead plan on getting a phono pre amp to go with the table along with a cartridge something like a Ortofon 2M red would work very well I think it could be a nice vinyl source. Its Not going to be the last word in detail and resolution but it will have a warm lively sound and great speed stability (direct drive tables have the motor connected directly to the spindle). 

I sold the technics 1200 series a while back. Good turntable. It's more of a DJ table then an audiophile one, but it's well built and the tonearm can handle most cartridges. Do not use the mixer. It will not improve the sound at all and most likely make it worse. You don't mention what cartridge it comes with, which will make a big difference in sound and cost. Also you don't mention your speakers/preamp, but I am assuming with a tube amp, you have a decent system. This would be a good table to start with if you are trying to decide to get into, or back into, records. You can check average prices on Audiogon/ebay and other sites, I saw many for sale.. Should be in low-mid hundreds, depending on the cartridge and condition. I would not spend more then that as you can get a better table once you get to the low thousands. Hope this info helps.

It’s an excellent turntable. I have one in my collection. For an alternate choice the Pioneer PLX1000 is an easy recommendation ($700). I have one set up with two cartridges on separate headshells: a Denon 103R and a Grado G1+. Herb Reichert gave it a very favorable review in Stereophile.