There's a lot going on in the amp that will make it sound different than a typical 12AX7 input kind of thing. The EF86 has enough bias on it that you would usually need a pedal with some boost to overdrive it, even a humbucker is barely going to get the EF86 crunching. On the other hand that single EF86 has a ton of gain and drives the bejeezus out of the EL84, particularly with the feedback rolled off. That's how the amp is capable of putting out around 10W distorted. So the sound is not only pentode distortion-dominant (duh), it's also output stage distortion-dominant. It gives it a wee bit more of a "big amp" sound that one would expect from a little practice size amp. In clean mode it's probably going to sound closer to a 12AX7 input amp, but the direct coupling and fairly high amount of global negative feedback that can be dialed in (about 20dB) should at least in theory make for a "cleaner clean" than some other amps are capable of - a bit more snappy and articulate.
