i solved this problem with a simple volume box in the effects loop (preamp out / power amp in). it is a simple effects enclosure with a volume pot that let's you throttle back the preamp volume before it hits the power amp. i have my master volume at about 9:00, and the channel volumes on my presets around noon, and can roll the output volume back to whisper quiet with negligible tone loss, and there is no pop when i change channels.
these things cost $20-30, or you can easily make your own for less than half that.
note: this is NOT an attenuator -- it does not 'swallow' power before it hits your speaker. attenuators are a whole nother thing, cost a LOT more, and suck tone when trying to bring a big amp to bedroom volumes.
Vick Audio makes one called a 'tube tamer'. or look for 'guitar volume box' on ebay. look for something that has an input, output, and single knob that costs around $20.