I find less volume and more or less gain and master works best for me.
for a fairly smooth clean grind on the lead channel: 65 watts/Deep/Bright settings, gain at 10 o'clock, Bass 11 o'clock mids and treble at noon, volume at 7 o'clock (barely breaking it open) and the density at 11 o'clock no presence or reverb (got pedals for that) then Master (main 1 around 1 o'clock with a little of main 2 about 7/8 o'clock for good measure) then I throw on a nice boosted drive/distortion pedal and walla a cleaner grindy saturation.
with these settings the lead channel doesnt sound like much on its own, its when you kick in the compressor and boost the drive pedal that it comes to life.
I find I get more of what I want by running pedals through the clean channel with lower gain and volume settings while cranking the master for power tube saturation, 65 watt, Deep,Bright settings, gain at 9/10 o'clock, Bass at 1 o'clock, mids at 11 o'clcok, treble at 10 o'clock, volume at 1/2 o'clock, density at 11 o'clock no presence or reverb (again pedals for that) Master (main 1 around 1 o'clock makin 2 around 7/8 o'clock throw on my compressor and drive pedals and whamo ! put that setup on the attenuator and BAM ! grind heaven.
For me I like getting my tone using a clean base and then using my pedals to tailor the sound while pushing the volume with the master for power tube saturation.
This way I can just tweak away on my pedals if I want to change things up or refine the sound....of course I dont live with only these amp settings I like to keep trying new approaches all the time thats when the magic happens, the trick is remembering what I did, if Im motivated I will write down my settings or use thin strips of electrical tape to mark them on my gear...it all depends on the day or night and how I feel...
I think your approach of using the volume at higher levels makes sense as your trying to avoid saturation from the gain, but overall I think its standard procedure to use the Master to boost your volume for power tube saturation, which is usually more desirable than blasting the preamp section.
I have found that less is more on most settings especially once I add pedals into the mix, of course you didnt say if your using pedals or not which of course will make all the difference in the world as its like adding another preamp section to push the amp, can get pretty tricky until you live with your gear for awhile.
Some of my gear is a little complex and it dosnt take long and I can f*ck up the whole setup if I get too out there tweaking away, which is why I have made it a habit to mark my settings, that way I can always get back to my base tone without having to reinvent the wheel again.
