My Warwick thumb 5 NT has always had a great interesting mid-dy sound, but since getting rid of the MEC stock guts its output has been lacking energy. Very quiet bass plugged in. I replaced the MEC stock with bartollini passive Js, and added an EMG BQC tone control. Even running at 18V or 24V, the output of the bass seemed lower than average, though the tone was always pretty good (and difficult to work with sometimes). I had always been bothered by the volume dip at 50/50 on the pickup blend knob (kept the MEC stock vol/balance/DPDT, and this passive volume/blend system was meh) Decided to get a U-retro 01, for the presumed better overall sound quality and especially for the active blend circuitry. The install was very easy! Everything was pre-soldered on mine. I had to cut the 1/4" jack that came wired and soldered those leads on the 1/4" jack that's in the warwick. The pickup leads fit nice into screw-terminals on the board. No soldering! This preamp came wired with two switches (blue squareish in cavity), one that disables the blend knob and defaults to 50/50 neck/bridge. The other disables the active circuitry. I probably will never use these knobs, so I tucked them in the cavity and avoided drilling any extra holes in this beautiful piece of wood. The sound is very very good. Amazing definition across the spectrum. There is no bass rolloff, only bass boost, it's odd not to play at the center detent (too much added bass by then). The treble knob can be lifted to add treble boost, which is nice for bringing out harmonics. Standard parametric mid. There is still a drop in character at 50/50 blend, but it isn't as bad as before. As soon as one pickup is singled out slightly, all sorts of character comes out, but dulls out a bit at center detent. The output on this thing is ridiculous! I feel like I should play at 80% volume or something. I lowered the pickups to try and compensate. There are trimpots for gain adjustments on each pickup input on the preamp, but they are +gain only and were set to zero. Not sure why this is so hot. Might lower the pickups further, or do a full setup (sigh) and find my bridge saddle a little higher.... Hope this is useful info for someone!