Hi Red Label, I appreciate that Splawn and Friedman amps must be very difficult to beat but you might also consider that the experience of dialling in the Yamaha is very different to most Marshall type amps. For example, when I use Marshalls I will start with the treble and presence set to zero and usually don't push them past 2 or 3 because the top end becomes unbearable. To produce Marshall type sounds with the Yamaha I've got the treble about two thirds to three quarters of the way up and the presence about half way up. If you try the Yamaha again I would suggest you set one of the channels in the following way - gain maxed, channel volume (master) about three quarters, bass and mids at noon, treble about three quarters, presence two thirds to half. Engage the boost (white boost) at a low setting and gradully turn it up. Select the Lead pre-amp into EL34s, class AB. I have both channels set up like this but with more boost and volume on channel two. If you are able to try the amp with the output volume about half way up do it because this amp likes to be turned up. Try the same settings but with the Crunch pre-amp engaged.
Maybe you just don't like the amp but I think some folks are dismissing it because it involves quite a learning curve to get the best out of it. I've been gigging a Cornford Roadhouse for about seven years and it is a great amp but the Yamaha is giving me the best tones I've ever had.