I am getting the UA and based on what I learned, it's allowing the power-tubes to get over-driven and then it re-amps or puts a load on the output signal before driving the speakers, resulting in the same amp tone just at a lower volume. It was this understanding that also led me to purchase my first NMV Amp, a Germino Lead 55LV. I'll get that great sound at a safe (both for my ears and my marriage) level. My question is: How does a master volume work in comparison? What is the source of the overdrive? I would like to understand the difference. It seems that NMV Amps are a Vintage amp feature, whereas Master Volumes are the standard today. I understand that the Magus Ultimate Tube Amp is adding Attenuation to their amps and have gotten rid of the Master volume? Do you suppose that that is a trend that may catch on within the industry?