I bought this as something "small" to use at home and for rehearsals rather than lugging my JCM900 head and 4x12 cabinet everywhere with me. When I use my JCM900 (100W) I get practically all of my overdrive effects from pedals, and only use a small amount of reverb on the amp, but wanted to keep things as simple as possible at home with having a good overdrive channel on whatever my amp was going to be. Having a bunch of high quality guitars, I wanted something that would compliment their quality so I wanted valve. This JCM600, was a great buy!
Bought for just £200 (poor cosmetic condition, often sell for £500+) I had enough "change" to revalve it, and daaaayum it sounded great afterwards!! The valves do rattle a bit, probably due to being horizontal, but that's not a deal breaker for a practice amp. The cleans are stunning for a relatively cheap amp, and the overdrive isn't far behind.
The clean channel really needs the bass dialled back at low volumes, but otherwise sounds incredible for its price. The overdrive channel takes a bit of time to dial in the right EQ, but once you find the sweet spots it really growls! Or sings if you want it to.. I was really impressed by the difference made to the tone by putting a patch lead in the parallel effects loop and turning the loop volume right up, seems to give it a massive tonal boost although I can't really put it into words...
Overall a great valve amp for those on a budget, you really can't beat it for the same money elsewhere!