Do you need an affordable four channel preamp? It would be hard to beat this TL Audio PA-2001. It’s a hybrid solid state and tube design. Each channel has a 12AX7 gain stage so with the input gain down and output up it can be transparent, but when you drive the input harder into the tube and dial back the output you’ll get some nice saturation. Each channel also has a high pass filter, phase reverse, and phantom power. All four channel works and sound great and the unit is in excellent condition for its age. $450. I could ship or pick up in Nashville preferred.