balanced power and ground loops

Blueswan is correct, except for the Equi-tech wall units. These are very large very high KVa. The Q design is for high current (particularly useful for amps). Their smaller component type units, I would agree should be left for source components.

The transformer accomplishes two things. One it creates balanced lines (+/- 55V) rather than 110V and a neutral. These are out of phase and thus have the noise cancellation properties mentioned above. The other thing a transformer of this type does is isolate the power for the audio room from all other noisy electrical components in the house. Separate circuits will do this to some extent--but not entirely. These transformers really work in that regard.

Blueswan is correct for the most part about current limiting devices, except for the Equi-tech wall units. These are very large very high KVa. The Q design is for high current (particularly useful for amps). Their smaller component type units, I would agree should be left for source components.

Balanced power eliminates what is called common mode noise. It is the same noise reduction principle used in balanced, XLR, cables. These types of power conditioners are generally transformer based and are recommended for low power devices like the preamp, CD transport, DAC, DVD player, tuner, etc. Unless you purchase a very high power conditioner, balanced power is not really beneficial for power amps because they can restrict dynamic range, or worse, overload the device.

I use a Tara Labs AD-10B. It has non-balanced outlets for high power components where I plug in my Sony Wega and power amp. Everything else goes into the balanced outlets. This also has the advantage of eliminating ground loops because everything in my system is plugged into it. Thus, there is only one plug, and its ground connection, to the wall... the AD-10B itself.