Folks,

Sorry if my reply is not technical enough for you but...

Almost any system is capable of generating "hum". In my many years of playing around with lots of different gear I've had it happen to me many times.

In some very rare cases it has been a defective product. So the first step is always the manufacturer / dealer etc.

But in a lot of cases they'll fire it up and won't hear a thing - because the problem is with your "system" as opposed that one piece of gear. And your system includes just about everything connected to your home's electrical system - from the breaker panel on in.

In my current set-up I'm using many pieces of gear (24 or more individual components). One of the things that I noticed last year (after I added an ICBM by the way) was a growing problem with hum: some fixed, and some variable. I tried all of the "easy" fixes; reversing plugs (where possible), separating (physically) components, keeping "power" and "signal" cables apart. Not running them parallel to each other etc. But the problem persisted. So I bit the bullet and bought an isolating transformer (sometimes known as a ground loop isolator.) It cost me over a hundred bucks (Canadian) at an electrical supply store for a fairly beefy unit but it cured the problem. In my case it turned out to be the four or five components that used wall warts - including the ICBM. To keep costs down manufacturers choose them over proper internal power supplies. To keep costs even lower they use really cheap wall warts. When I powered all of mine from the isolated side of the transformer the hum problem went away. I might have accomplished the same thing had I put my pre/pro (not yet a 950) on the other side instead. It may or may not work for you.

So my not-so-fancy solution to hum problems, when all else fails, is to try the isolating transformer route. You might even be able to borrow one from a supplier to see if it will solve the problem before you purchase it.

Hope that helps.

Jeff