Pretty amazing how much opinions on guitar amps can differ from person to person. I rarely design for predominantly power amp distortion. It never has the edge that I like. To my tastes, I find the best sounds come with the right balance between preamp and poweramp distortion. As they say, your mileage may vary...
And I absolutely hate tone stack defeat mods in any amp I've ever played or built. Recipe for mud IMO. The only 'single knob' EQ I like is the Tilt control (Big Muff Pi, etc), and even that I find extremely limiting.
I've never been super impressed with 6V6 or EL84. 6V6 is ok, but I don't like EL84s at all. For me, KT66 and KT77 is where it's at. I prefer 6AQ5 over 6V6, although maybe that's because you typically run them at a lower voltage so there is less headroom. Electrically, they are pretty much equivalent.
Here's a short clip of a 6.5W push-pull 6AQ5 amp I built called the Lucky 7: http://www.macjams.com/song/63549
. The topology is 6AK5 (5654) pentode input stage with variable triode/pentode morph control --> variable coupling cap (a la Orange FAC control) for bass --> treble cut control --> 6J6 (5964) floating paraphase phase inverter --> a pair of 6AQ5 --> 15W 5k:8 ohm output transformer with the screens fed via an ultralinear tap on the OT.
This amp has great touch sensitivity. I have since installed a switchable 6AV6 boost stage, so it can go into huge levels of distortion as well. The project was based on a challenge to design an all 7-pin push-pull amp. I'm still not satisfied with the tone controls so I'm planning to pull the FAC and treble cut and install a Bone Ray tone stack (Merlin Blencowe's creation).
There are a couple of pictures + some of the early schematics here: https://plus.google.com/u/0/photos/116886998028395181572/albums/5491186118511677249
I've changed the phase inverter considerably since the last time I posted a schematic, and the biasing on the input 6AV6 stage is considerably different now. I'll have to re-trace the circuit and post updates at some point, along with some finished pictures.