Kit, I honestly do not know why u would get a buzz now that u did not have b/4. That is kinda strange. Did u plug something new on that same circuit like a computer, printer, modem,...........
I agree with Atmasphere about determining if it's the pre-amp or amp. Willing to bet it is going to be the amp.
In my situation, I purchased a brand new McIntosh MC205. And had a buzz in the #5 channel. I did take it back to where I bought it from but they did not hear the buzz. Said that I had a ground loop problem, etc etc etc....... I did all that unplugging and moved cables and still have that buzz. While researching my problem I found that the use of the cheater plug removed the buzz and it did work.
Yes, using a cheater plug is and may not the best way to go. For me I use a cheater plug for my MC205 plugged into a dedicated 20 amp circuit. I am not too kin in doing that. I do not like the fact of removing the ground plug, but it works for me. I plug and unplug my amp when not in use. Sometimes I will go 2 - 3 weeks w/o listening to my system so unplugging it is not a bad thing.
Hum X is a product that takes the buzz away for about $70. Cheater plug: $00.70.
Please let use all know what is causing your buzz and how u removed it. I am very interested to know.
Thx and good luck
