ELDARTFORD: As for balanced circuitry in the power amp the advantage over single ended is largely theoretical for well designed equipment. It is often said that balanced is quieter because the signal is twice as strong, but there is also twice the circuit noise. Common mode noise, as for hum from the power supply, will be canceled, but there shouldn't be any such noise in a good unit.Circuit noise is not twice as strong (+6 dB) in balanced designs. Rather, it's +3dB stronger, due to stochastic signals adding up logarithmically. That gives balanced units a +3 dB advantage in noise over single-ended ones. You are also neglecting the benefits caused by reduced distortions caused by cancelling, as well as the improved stability at the power supplies. The advantage is largely theoretical for BADLY designed equipment. In well designed units, the advantage is subtle but real, and I think detectable by ear if you care enough.
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