Torres British Invasion

There are two versions of the two-channel British Invasion, a 20W and a 50W. This is the 20W, with a pair of EL84 power valves and an added Gain control. This one too has been built with carbon film resistors and Sprague orange drop caps, all engineered for a British sound.

Sounds
These amps have identical speakers and similarly-sized cabinets, but they sound quite different. Starting off with the Normal input it's apparent how much more clean headroom the British Invasion provides. It's also far more transparent, and although it doesn't do Fender silverface levels of brightness, it does get you close to blackface territory.
With Master volume turned fully up, you can get the input volume control up to about halfway before overdrive starts with a Strat, and it only really starts to kick at about two o'clock. There's also plenty of tonal variation, because the equalisation controls are very effective.
Dialling out the mids and boosting the treble and bass produces some convincing funk and country sounds. With PAFs the overdrive comes on sooner, but there's still plenty of volume, and as long as your pickups aren't wound too hot you can get some warm, woody jazz tones with impressive articulation and clarity.
Pushing the Normal side harder, the Torres BI reveals an overdrive character that's smoother and sweeter than its little brother. A Les Paul conjures a first-rate blues sound with no mushing out at higher volumes - in fact when it's cranked up and a bit of power supply sag starts to dampen down the transients, the Invasion sounds clearer and more composed.
The extra gain control only works on the high gain input. Single coils aren't powerful enough to push the Normal side beyond bluesy overdrive, but the High Gain side takes over to produce ludicrous gain levels if required. The upper harmonics get so saturated that the neck pickup tone control on the Les Paul was rendered almost ineffective.
This channel is equally adept at subtler gain textures, with a slightly fatter midrange than the normal channel. You can use an external A/B switch to go from clean/overdrive to heavier overdrive/crunch, and that master volume control keeps things under control without messing up the basic tone. Early Clapton, Zeppelin, '80s ZZ Top, the heavier moods of SRV - those tones are all in here, and they're easy to find.

The British Invasion is great for low volume crunch... and a lot more besides. The two channels make this amp much more versatile, but it'll be running louder before you'll hit the sweet spot if you're into power amp distortion. To be brutally honest the standard of finish on these amps isn't exactly top drawer, but I've seen far worse on some American boutique amps costing far more - and both these amps are such wonderfully responsive tone machines that the asking prices made me do a double-take. If you're prepared to try building (and covering) one yourself, you'll be getting the best of boutique at an even better bargain price.