I've had this amp since high school. It has had maintenance. It has sounded pretty good at times. I mainly use the clean channel. But my 68 Vibrolux Reverb (blackfaced) makes it pale by comparison. The Concert can sound a little cardboard-y dull if the treble is down, or piercing if the treble is up. The lead channel is muddy and tubby. It is hard to find a handwired amp, this portable, and with this much clean headroom. I bought it for $450 20 years ago. There are techs who like to mod this amp. It's just hard to go that route without knowing the outcome (I'm picky). Should I mod or should I sell (if this circuit is just too different from the bf cleans I love)? This might be a question for the technical area too.