I found that on paper it's an almost perfect amp but in practice it doesn't deliver. I found the gain channels to be way too fizzy and it had this frequency that caused me massive ear fatigue even at low volumes.
You mean 5751 in place of the v2 12ax7 right? I did the same.
I think this amp is underated too. Well thought out controls, lots of features, nice price, made in USA!
It seems the biggest complaint is that it can be fizzy. It's true that it can make some thin fizzy sounds, but it can also make some great ones. Three voices per channel plus eqx makes for a lot of possibilities and they aren't all good. I did have to spend a little time getting to know the amp, but have actually come to like it more as time goes on. I hear people say the same about some mesas in regard to having to learn them.
I don't think it's the end all be all, but you get a lot for your money and I think I'll be happy with it until I can afford a very expensive upgrade.
I used to own both the original V3 (pre-LED's) and the V3m. Really tried to like, but in the end it was fizzy, inorganic, and generic. Neither wowed me, and I had hoped that the M was going to correct some of the deficiencies of the big V3, or I wouldn't have bought it. Priced well, but you get what you pay for.....meh.
My experience was the same as most of the above posters. I kept it for almost a year, did multiple tube swaps, never got what I was hoping for out of it. When the reverb acted up, and Carvin repaired it and refreshed it at the factory, I decided to quit trying so hard and move on. I have a Victory V30 Countess with EL34's as a replacement and I'm much happier with it than I was with the V3m. I'll admit, the V30 cost considerably more than the V3m, but I'm spending more time playing and less time tweaking.