Fantastic amplifier. The two different preamps have different enough characters that it feels like you're getting two amps in one. The poweramp switch gives you a couple more combinations, but the differences there are more subtle.
I've owned plenty of amps (Marshalls from a Superlead through a 2203 and JCM800 and JCM900 channel switchers, Fender Bassman, Peavey Classic range) and played through many more, but frankly this is the only amp I've ever used with more than 1 usable sound! The ECC83 channel is chimey and dynamic; I generally play it with the volume half way, at which point it's just starting to break up with P90s or humbuckers. The EF86 channel is softer, darker and breaks up more easily; I play it with the volume on full, where there's plenty of overdrive. Unlike reviewers on other sites I don't think it sounds particularly Marshally; it's better than that! Compared with, say, a Superlead, the overdrive is smoother and there's more of it.
The amp has a 12" Celestion Heritage Greenback speaker. I also played the head and matching 2x12" cab in the shop. The cab has Vintage 30s which are brighter and stiffer-sounding - I prefer the Greenback.
I also use the Blackstar HT Boost as a treble booster to overdrive the preamp still further for the odd solo. This combination sounds great together - smooth and saturated. Don't put an overdrive/distortion pedal in front of this amp - there's much cheaper ways to amplify the sound of your pedal.
The only downside, of course, is that even at 5 or 15 watts, this amp is too darn loud. It will be loud enough for the vast majority of gigs. It's inconveniently loud for practice or recording. The volume controls on this amp should be used to get the sound you want, so you'll need to invest in a decent attenuator to get that at a level your neighbours can live with.
Actually there's another downside - for a 1x12" amp, this thing is big and heavy. On the other hand, as a result you get a much bigger, fuller sound than you'd expect from a 1x12.
