I've been shopping around for a nice all tube amp for not too much money and I found someone selling a Carvin Valve Master Head.

I read a couple reviews online but in general I haven't seen much about them. The people who do have it say it's great.

Anyone have any experience with these amps?
I don't know the amp in particular but Carvin stuff is normally pretty good. I just had a look at the schematic and it looks fairly decent. I can straight away see scope for modding it though. It has clipping diodes between V2a and V2b. I'd be replacing those with a 1M resistor asap but otherwise it looks like a good honest valve amp.
Gilchrist custom
Yamaha SBG500
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100

Cathbard Amplification
My band
Yeah, I've got some experience with Carvin Power Amps, and in general they're solid and sound pretty good.
The Carvin VM 100 was a very good amp back in the 1990s. It sort of gave way to the MTS series, which was replaced by the revamped XB-100, but it was a fine amplifier in its own right. If it is in good shape, it should serve you very well.

"Maybe this world is another planet's hell?" - Aldous Huxley