Kijanki, I have to straighten you out on a few things!
1st- the use of balanced line is lower noise from the cables no matter the length, assuming that the input of the amp is properly designed.
2nd- the even ordered cancellation thing the way you are presenting it is incorrect! How that works is an amplifier that is fully differential and balanced will have even ordered cancellation **from input to output**, not just at the output. What this means is that less distortion will be compounded from stage to stage. If in the case of a tube amplifier, this means the primary distortion product will be the 3rd, which is still considered musical to the human ear. However it will be generated at a much lower level than the 2nd would have been!
At any rate you are not removing even ordered harmonics from the signal- all you are doing is preventing even ordered harmonic generation, which means the circuit will be more neutral.
3rd, the idea that the signal goes through many more stages is a myth. In our amps, the signal goes through exactly one stage of gain, which is less than most entirely single-ended amps. The complexity of the circuit is not the same as the signal path! Our preamps have only 3 stages of gain from the LOMC phono input to the line stage output. Thats a fairly simple signal path compared to almost any preamp. Additionally the output impedance has no bearing on the fact that the amplifier is fully balanced/differential.
Since outputs have no ground reference (current doesn’t flow thru
ground) feedback might cause instability. That requires additional third
feedback for common mode.
Again, I don’t see how this scheme can
help with noise. In addition even connection with XLR cable is not
always the best. If you don’t have a lot of noise you might be better of
with plain single ended RCA since additional circuitry to make balanced
output affects sound.
Essentially the statements in the above quote are false.
@nyhifihead,
if you are looking at solid state amps, the McCormick and Pass amplifiers are quite good and accept a balanced input correctly (many high end audio amps do not, likely because the designers don't know that there is a standard for balanced line operation, defined by AES file 48).
