Warwick Quadruplet tube preamp. - Quad-matrix: four different preamps in one, basically -- four different voices accessable at the flip of a switch - powerful EQ: four-band, with "shift" switches for each midrange (lo-mid and hi-mid), plus "low-boost" and "high-boost" switches - tube overdrive control: "crunch" knob turns up the tube gain and turns down the output gain at the same time (so the total volume stays the same) - three preamp tubes and one power tube w/ internal dummy load (like the SWR IOD) IMO the "crunch" knob is more of a "warmth" knob - up all the way the sound is definitely overdriven, but in the middle mostly it increases that gooey tubeyness. Has an effects loop and pre/post DI output. It's a lot of preamp stuffed into a single rack space. Purchased earlier this year from a fellow TB'er. The only problem I've had with it was ONCE when I first got it, it would turn itself off right after I turned it on. It did this for a couple minutes (just enough to make me panic), and has worked fine ever since. Don't know if it was cold or what. Asking $500.