ahhh for the sake of conversation I will contribute 2 cents (and not a penny more)
The single channel chan dual mode provides a player the unique ability to tweak tones in a way unlike most modern amps. The cascading signal chain in lead mode with the vol 1 allows fine tuning of the gain that expands the possibilities. You can chug with the Vol 1 cranked but you can get cool cleans and edge of breakup with dialing the gains back and then everything in between. That is the advantage IMHOThe granularity with these adjustments poses a compromise as yes.. constant adjustments are the norm and there is that compromise of clean vs lead live.
The modern Marks V may have that one IIC+ tone locked in, but they can't really duplicate the other areas of the IIC+ that you can tweak in.
Ah the source of never ending tweak-a-loo of my long gone Mark III - the reason I finally let it go. Clean, crunch and lead levels/tones always were impossible to get right on live environment. 1,5 -> 1 ¾ master volume bump deafened everyone and all mode volumes were off… as a corrective measure I built a pedal board with Carl Martin analog controller to have certain boost on crunch before amp for gain and in loop to raise the volume back to unity with clean and all the other modulation/delay. That was heavy as hell with other pedals
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Thanks for reminding me about this feature. Mark V is really good for me thanks.
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Yet.. would be nice to test the VII or JP2C