If the entire audio system is done completely balanced, which requires a four channel DAC analog filter and audio circuit set, a four channel preamp, and a four channel power amp (or two stereo power amps) maintaining balanced operation from input to output, summing the signal at the speakers, then in theory, all common mode distortion in the system will cancel, providing superior musical operation, depending upon how much distortion was there to cancel. This is usually only possible with a DAC source where both plus and minus left and right signals are available from the source, depending upon the DAC chip set in use.
We actually have tried this with positive results. Of course it essentially doubles the cost of the audio system.
However, in our case, the audible improvements alerted us that since the process was better sounding, then there must be distortion components in the audio chain that were being canceled that we had not yet addressed.
This sent us on a serious effort to discover the remaining weak links in the audio chain we produce and fix them if possible. The result was significantly improved performance for several of our products, resulting in only minimal improvements when those improved components were once again tried in a full balanced system. This made the thought of actually doing a full balanced system not cost effective at all. But the exercise sure was helpful in putting up red flags that we were not as good as we had thought we were and helping us make things better.
Regards,
Frank Van Alstine