Does the volume setting on the cab or any of the post amp effects affect the tone in any way, or is it simply a volume adjustment (not including the Fletcher–Munson effect). I can see where a pre amp effect volume adjustment would change the gain and tone of the amp, but I would expect that the cab and effects after the amp wouldn't affect the tone as you adjust the volume parameter, they would simply change the volume.
And for you grammar guru's, I still haven't figured out how to use the words "effect" and "affect" so please take it easy on me