Balanced lines solve hum problems?

I'm having a real tough time killing a low level hum coming out of my Martin Logan Quest speakers. The set up consists of an Oracle Delphi IV and YBA CD Integre source components, fed into a Audio Research SP9 Mk II Pre-amp. 25' single ended interconnect to a pair of bridged Classe Audio DR-8 amplifiers. From there, (8) 8' runs of speaker wire to the Quests complete the system. I've put in hospital grade plugs, and grounded the amps to a cold water pipe, a little better, but still a hum exists. One of the guys I work with feels I have a 100hz hum, likely coming from a motor (i.e. fridge). He has suggested I change from single ended to balanced lines, and the problem ought to go away. To do so, means inserting a DI box in the signal path to convert single ended to balanced signals, via an isolated transformer, I'm not in favour of this approach. Another option is to sell my Audio Research pre-amplifier I love (great phono section) and find another pre-amp with balanced outputs, more than likely a line stage pre-amp that requires a seperate phono stage. Much money and hassle, is this the only way to solve this problem? Opinions are most welcome, thanks, Jeff
I don't know if that's the ONLY way to solve the problem of hum induced in long single-ended interconnects, but it is the only way I could solve the problem in my system. I tried a lot of different things, but the day I hooked up the balanced output of the Bryston BP-25 to the balanced input of the Aragon 8008BB through AQ Opal, the hum was GONE. DEAD silence, with just a slight hiss actually caused by the CD player when turned all the way up with nothing playing. The empty input positions were DEAD SILENT. I will never go back as long as my amp and preamp are more than three feet apart. Right now they're close to 30! It is a big hassle to switch, I agree. Take it one step at a time, watching for deals on good balanced gear. And beware of some amps that have "balanced" inputs, but merely hook two pins together in their single-ended circuitry. Hummer bummer.
Balanced cables will solve the problem if its radio frequecy interference. You should disconnect your preamp and amp and then listen for hum. If its still there its probably an amp problem. You mentioned a refrigerator motor. That's easy. The motor doesn't run all the time so when the compressor is finish cooling down the frig and the motor goes off then the hum would go away. More likely its your preamp. I owned an ARC LS2B and used it in the balanced mode. It caused hum and when I connected anything associated with the TCI/AT&T TV cable system the hum got unbearable. I changed to a Sonic Frontiers LS3 and the hum went away. Are you using the three prong power plug on your ARC or did you have to use a cheater and go to just the two prong configuration? I had to do that the day I bought the ARC. This work as long as everything else behaves properly vs grounding.
Thanks for your responses, appreciate it very much. No, I'm not using cheater plugs at all, I've considered it, but there are certain disadvantages to floating grounds. I'm leaning towards getting rid of my cherished pre-amplifier (wouldn't be too tough to sell here at Audiogon or at Audioshopper) and going to a balanced configuration. I suppose my next step would be to solicit opinions as to a suitable preamp that has similar sonic qualities to my AR. Keeping in mind my devotion to phono, need for a tubed product (or tube-like characteristics) to tame the solid state amps and electrostatic speakers, and a balanced connection scheme. Fortunately, I don't give a damn about video stuff, so there are no HT concerns. Ideas for the ideal preamp without breaking the bank (~$2000-$2500)?
Got no bal. help/experience. In my setup Joule Electra with their outboard ops-003 I can't use the ground at all.---Tried no phono ground?