And the answer is... Zero hum with either pup soloed in active mode. Zero hum with either pup soloed in passive mode. One again East delivers the goods. I ran both active and passive tests at full volume with the treble pot dimed and the bright push/pull engaged. If it doesn't hum under those conditions it's just not gonna be a problem. Unfortunately, I realized my output jack is starting to go; got a loud pop if I wiggled the cable. No big deal, I have almost ten years on this preamp an a new jack is an easy DIY job. Hope this helps.