It doesn't sound normal. Try reversing pre-outs. Does the left speaker make the low hum. I think you might be blaming wrong component. See an "audio troubleshooting guide."
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How long does the hum last for after you turn your amp off? I suspect the right speaker is experiencing more interference probably due to the cable being crossed with another cable. When I turn off my aleph3, there is still enough power to play music for about 2-3 seconds. So, there is definitely juice left in the amp even after turning it off.
Thanks for all your responses. I've tried all combinations to isolate the "problem" but have narrowed it down to amp residual noise. If I remove all cables but speaker cables from amp to speakers I get a slight hum from right speaker. I tried swapping speaker cables left to right and right to left and problem remains the same side(right channel). It is not the preamp or any associated cables as I have tried all combinations. I as well isolated all ac cable from each other.My Pass X250 will have a slight residual hum from right channel but it is only noticable if I put my ear right up to the speaker and I was wondering if anyone else has experienced this with there amp and could it be normal? Thanks again
THANKS SEAN, BUT I HAVE CONTACTED PASS LABS AND THEY CLAIM IT'S NORMAL. I DON'T KNOW WHAT TO THINK. I PREVIOUSLY OWNED A CLASSE CA201 AS WELL AS A CLASSE CAP150 INTEGRADED AND THEY BOTH DID THE SAME THING.I'VE EXPERIMENTED WITH SWITCHING AND SWAPPING INTERCONNECTS AND POWER CORDS AS WELL AS ISOLATING ALL CORDS AND USING DIFFERENT OUTLETS. PASS CLAIMS IT'S DUE TO THE TRANSFORMER HAVING WIRES GOING TO IT FROM ONE SIDE ONLY AND THAT THEY COULD ELIMINATE THIS VERY SLIGHT HUM BUT AT THE EXPENSE OF THE SONIC QUALITY OF THE AMP.IT REALLY IS ONLY NOTICABLE IF I'M INCHES FROM THE SPEAKER BUT I DON'T KNOW IF THIS IS NORMAL.
MITCHb, I can inform you that after your thread I give a check to my Pass Aleph (class A single ended amp). Turned it on, and noted exactly what you described. I have both speakers the classic background hiss + a very slight bzzz from right speaker.
The fact that I catch it just after your thread means that it is really very low in intensity.
If this is the case, do not compromise with sound quality and just keep it as it is.