PEAVEY 6505 VS 6505+

Wait what, the two amps while being similar are substantially different, period. The red channels there is a small bit different as can be easily seen by taking a look at the schematic. The MkII also has less gain in the red channel due to changes in the first gain stage which also effects the green channel and does change tonality somewhat, less highs, more low end, meaning the MkII isn't as tight. Of course the biggest difference is in the green channel which is entirely new/not seen in the MkI and that is the biggest change.