Hi. I've owned a Groove Tubes preamp for about 4 months. . . I forget the model name, but it's actually the front end of an SWR SM-series amp, without the power section. Anyway, some of my basses (those with hotter pickups/preamp) have always sounded great going thru this unit into a Carvin 600-watt power amp and a Bag End S15D. However, a couple of my basses sounded muddy and lifeless. Last night, I decided to play around with tweaking the knobs on the preamp. What I found was that each of my basses sounded INCREDIBLE if I just cranked the GAIN knob to the point of clipping, and then backed off just a hair. Apparently, as long as I was giving the preamp tubes as much gain as they could tolerate, they responded by generating tons of warmth and clarity. Anyone else find this with their SWR SM-series gear? BTW, I know I'm dumb for not having noticed this sooner. . . .