hi there i just received my russian muff.i also bought a 9V to AC adaptor.i tried it and it sounds quite good to me.but there is a big problem.it hums heavily whenever the sustain knob isnt at 9 o'clock(at this position there is also a little hum).i love the sound when the sustain is full on,however it is unusable due to the hum. also,when my volume setting is lower than 11o'clock,there is little hum and VERY little gain.but when i turn pass that,the hum comes in a terrible way.and this is annoying cuz i have to get to 12 o'clock to match my original gain. one more,it hums even i turned the volume on my bass to ZERO.any ideas? thx a lot. Sid PS:i use a cheap yamaha bass and a small practise amp to try it.even the muff hasnt a true bypass,there is no hum in OFF mode.