Cary SA500.1 mono blocks


I just added the 500.1 mono blocks and I have a hum on both that I can't get rid of .I've tried to lift the ground pin on the PS audio AC12 power cables with no change. I tried different power cables with no effect. The amps are on their own 20amp circuit plugged into a Richard grey 400 . Any help would be appreciated thanks .
128x128kwa69
Al, good catch as usual. KWA should call Cary on this. If this is the issue, he could damage the amps. BTW, the first iteration of the manual did not have that warning. It was added after the issue was observed by owners.
Thanks for trying to help me .I think the amps are fine it must be a ground loop issue that I can't fix .I did lift the ground pin on my power cables with no effect.The hum is coming from the speakers not inside the amp itself.I don't have any other speakers they are all Martin Logan and need a power cable wow I never thought I could damage an amp buy hooking them up to Logans that would suck.I will try different speakers tomorrow. I just finished putting my system back together its been a frustrating couple of days I might take a day off .
Hello I just wanted to give yall an update. It's been a few months since I returned the amps . I gave up on buying amps for a few months but a couple of weeks ago I got the bug again and started looking again. So I called the same guy about some other amps he sells. He told me he just talked to Cary and they told him to open the amps and check for a loose connection. Well he said that was the problem . He asked me to come up to the store he would show me the problem so I did. I saw the connection that was the problem its was a quick connect that got loose when they got shipped back from Cary . So I took them home to try them again. Well they are not coming out of my system this time they sound great. He gave me a great deal that that couldn't say no to. So all is good they have been in my system for a few weeks and they sound fantastic with no problems and most important dead silent.
Kwa,
Glad this was something minor and you got it fixed. If you need tons of juice, these are good amps.