So there's one and only one thing in the studio here that introduces ground hum. A power supply for a tube mic. Everything's on one isolated circuit BTW. A 3 to 2 prong ground lift adapter will silence this nutty piece o' hummin gear, but is it safe? (This mic will be used for a D/I'd electric guitarist who will be simulaneously playing and singing). If it isn't safe are there any good alternatives? Rewiring the mic cable? using one of those isolation transformers? Is this common or is the power supply potentially wired wrong? tHanKYa.