One question which keeps coming up over and over is the controversy regarding audio components being "fully balanced" versus what is sometimes referred to as "balanced converting to single ended" or "differential amplifier balancing".
Popular mythology has seen fit to 'bless' the concept of 'fully-balanced' This approach completely misses the point, which is, of course, to eliminate hum and noise picked up by the audio cables feeding the component.
The reason for this is that a differential amplifier ‘rejects any common-mode noise’ which appears at its input, by a factor equal to its common-mode rejection ratio (normally over 1000:1). A 'fully-balanced' circuit has a common-mode rejection ratio of precisely zero, since all signal, common-mode or not, is simply amplified and passed along via the two signal paths. It then remains up to the following component to attempt to reject that amplified noise, if it has a differential amplifier.
Thus, fully-balanced circuitry passes along any noise which might be picked up on the cables. Then it hits the final component in the system, usually the power amp, where the differential amplifier at its input is left to deal with the sum total of the common mode noise in the signal path (multiplied by all the gain in the system). If each component (source, preamp, electronic crossover, power amp) had its own differential amplifier input, it would cancel any common-mode noise which appeared ahead of it, rather than amplifying it.
All the above simply points out that what has been called fully balanced circuitry has a host of disadvantages, from cost to noise overload, to complexity and reduction in reliability. It has no useful advantages in the digital or analog signal chain beyond the microphone preamp. Bryston audio components all operate their balanced inputs on ‘differential amplifier technology’.