I owned
a Carvin V3 and accompanying G12t-75 half stack.
Here is my experience based off of this setup. I think the V3's strength is higher gain stuff. I think it does a decent heavy distortion and lead, though I think kind of confused on what it is trying to be like. I really did NOT like this amp with light to mid gain, sounded harsh and chords did not form well sonically. Overall kind of a fizzy amp, specially with presence up anywhere past 2. The clean channel sounded kinda wierd to me, had this odd mid honk to it or something.
So I no longer own this amp. Though I sold it to a friend, who plays a carvin guitar, and with his pickups, the amp sounded much better then with my guitar. He got some better tones out of it, and was completly happy with the amp.
So, my main complaint was that the mid gain really wasn't pleasant, at least with my setup, harsh, fizzy, brittle. I don't think the cab helped in any sort of way in regards to pleasing tone. I am sure with a different cab at the time, I would of thought a little better of the amp.
Nice features in it though.