Slight humming noise coming from Mark Levinson 331


I was changing an LP last night and noticed a very slight hum coming from my amplifier. I have owned this amp for about six months now, and just noticed the noise. It is not noticeable while listening to music, but you can hear the faint hum from a few feet away provided the room is super quiet. Is this normal, or should i be concerned? I bought this amp used from a authorized Levinson dealer and have not had any problems with this amp at all! Just wondering if this is normal, or am I going to see smoke and flames in the near future? There is no buzzing or hum from the speakers at all, just the amplifier. The amp is plugged into a Transparent Power-Wave 10 power conditioner. I have tried plugging the amp strait into the wall and it still makes the humming sound! Thanks for any input on this issue!
rick_hilton
In my equipment ML 331 is very nice and never lsten noise o humming!
Is better that somebody checking his power line at home!
hi Rick, i know it has been over a decade since you had that humming noise in your Mark Levinson 331.  i got the same thing in my 332 amp.  did you ever figure out what the cause of that hum was?
eelnad

The ML 300 series were plagued with poor OEM power caps so my guess is if you’re hearing a hum it’s the caps. Surprised if it’s the caps that you made it this long without having to recap. The bad news is if it needs recapped good luck getting it done through HK/ML but you should be able to find an independent shop to do it. Unfortunately it will not be cheap but you have a great amp and you’ll never replace it for the 1K or so it might run you to get it fixed. 
First step is you might have a ground loop so go to a hardware store and buy a cheater plug if you don’t have one to float the ground. Secondly make sure all your interconnects are away from power cables. If neither of these work take it to a tech to have it checked out. Again you have a great amp and definitely worth fixing if that’s what it needs. Good luck.