Maxon D&S Distortion/Sustainer

I have recently been looking to update distortion pedals and chose this particularly as it has no high mid boost. It's NOT a tube screamer, but acts right across the frequency range. (Just as I wanted !).
On first installing it on the pedalboard and switching it on I noticed faint mains hum. Not too surprising, as I was using a Telecaster with single coil pickups. It's just that I've never noticed it at this level before. Why not ? The D+S has extremely powerful gain, which is all part of the sustain capability and deliberately part of the design. Eventually I discovered that backing off the blend knob to 9 o'clock allowed it to be lost in the distortion. The distortion level is at 11 o'clock, with the tone flat out to give that "Holy Grail" sound that I've been looking for more than 10 years.