Lifting ground my only option so far?

Hi. Just this week I received my ATC SCM150ASL pro active speakers. They sound incredible. Thanks to Phil for a great deal on these used but tremendous speakers.

OK, so I had been using some VMPS RM/X's and had driven them with an old Krell KSA-100 amp. I'd always had the Krell plugged either plugged into the wall directly or first into a PS Audio ultimate outlet, then the wall. In either case I'd used a good audiphile-level power cord (bright yellow male receptacle but don't know the brand), but it was two-prong. Any three-prong pc would induce a buzz (not ground loop hum, had that a couple of times, solved it and know that it takes on a 60hz deep hum). I always assumed the buzz was coming from either the Krell directly or some faulty cable in my spaghetti-like HT system. But a two-prong ac cord always fixed it so I never looked further (would try Krell with grounded 3-prong whenever I added new gear, etc but would always revert back cuz of buzz). I know it's not the safest (although not really sure why) but it fixed the problem and I lived with it for many years.

This week the ATC's show up. (Note: The system today is much simpler, no spaghetti, everything is very accessible, and supposedly clean) The ATC's require preamp cabling with an XLR connector; my Modwright pre is unbalanced. While waiting for my custom Audio Art rca-xlr cables I found a pair of RCA-to-XLR adapters so I went that route out of impatience. I plugged both active speakers into the wall with either VH Flavor or Signal Cable Magic Cable power cords (3 prong). Buzz!!! Now the ATC folks, as well as some forum discussions, say that the buzz could be caused by the unbalanced/balanced cable, and that I might need to unhook the screen at one end (I don't know what this means let alone be able to do it). However, I'm still assuming the buzz is the same one left over from the Krell example (obviously it's not the's no longer in the system). So I put my bright yellow 2 pronger on one speaker, and a cheater plug on the other and voila, the buzz is gone and the music is incredible. New Audio Art cable arrive today. Installed it. Same problem, same solution.

Why write all this nonsense? Because ATC tells me I shouldn't lift the ground of their speaker/amps. I don't know how to unground the interconnects, and feel that the gremlin isn't them anyway cuz this beast has been around for years locked away in 2 prong-ville. I tried unplugging every combination of source, preamp, cable box, etc. I disconnected the cable tv, I tried the amps in other outlets, I disconencted the sub (even though it's not currently in the signal path anyway), is still there in 3 -prong land. Could it be my outlets? The line that the amps use has a four-gang on the front wall and a duplex on the side wall. One speaker/amp uses the side wall, one uses the front...and the front 4-way seems a bit loose in the wall...pushed back slightly from the wall itself. Could that be something?

Thanks for any help....

Well, I tried the idea of plugging both my Power Plant P300's (they condition all my equipment except the amps) into the same line as the amps. Previously they were plugged into long extension cords into an outlet in the back of the room, who's line is shared by my home office (pc's, etc.)

After step one (and re-replacing the power cords of the sepaker/amps with 3 prong) the buzz is noticeablly less, but still there. I then ungrounded both P300's and the buzz is basically gone; not quite as perfectly black silent as ungrounding the amps, but basically unnoticeable at 12 feet, and supposedly MUCH safer. Wish I could lose that last 2-5% though.
About a year ago I bought a Bel Canto eVo 6 ampilfier to power my front three channels and immediately installed it that evening. It sounded excellent. The next morning, however, there was a loud buzz coming from the L/R/C front speakers. I called the gentleman who sold me the amp and he said it sounded like a ground loop. I had never noticed ground loop problems in any of my previous systems. After extensive research,trial and error, and lots of help from Andrew Conley of Psiber Audio I have eliminated it and greatly cleaned up my AC. The main culprits were the satellite and antenna cables connected to my HT beast. I bought a ground loop isolator($10) from parts express, recommended by Chris Hoff at BBT, and it eliminated 90% of the buzz. I also removed all the flourescent light fixtures and light dimmers in our apartment and after each step the buzz waned. I also grouded the rooftop FM antenna to the same place where the building's AC is grounded. That made a significant improvement as well. I also grounded my AV reciever chassis which helped. My system is now dead quiet and I have peace of mind knowing that everything is safely grounded and my AC is much cleaner.
For some reason, I think Tri-path amps that are powered by AC are sensitive to AC problems which is not all bad. They are excellent tools for analyzing the quality of your AC juice.
I hope this is helpful.

Rather than guessing at what the problem is and trying to band-aid it, do things the right way. You've got enough money invested in your gear that it deserves a verified good AC circuit and proper system installation. Sean
Thanks. Why didn't I think of that. Do things the right way. Ok, thanks.
Sorry for being a smart-ass, but the first time your response posted the link wasn't there. All it said was "Rather than things the right way"...which didn't leave me much. Now the link is showing and I'll go get educated. Thanks...really.
I replaced one of my outlets (right speaker and one of the P300's) with a Porter Port (cryo'd Hubbell, I bought 4 the other day to address these issues regardless of the source; can't hurt) and will get to the 4-way asap, but it's tough to get to. I'll also put a GLI on the cable tv coming in, although disconnecting it did nothing earlier.

It's not ground loop though, unless that hum can be a much higher pitch than 60hz or 120hz. This I'd call a buzz...and it was clearly a buzz killer..:>)
Most hmmn noise is generated from Cable TV.
Do you have any type of video connected into your Audio System ?
If so disconnect the RF cable input and see if the humm goes completly away.
As stated in the original post "I disconnected the cable tv".