What really matters is if the audio equipment has a “true balanced” design. Meaning that there is identical circuits for the positive and negative signals. This means twice the parts and cost pretty much. Twice as many tubes or transistors and a higher current power supply to power it all.
Many companies just add XLR jacks to their single-ended equipment and add an extra IC or transistors (if solid state) or extra tube/s (if tube) to take the signal from balanced to single-ended. All this does is add extra circuitry and actually (typically) degrade the sound. All your doing is adding extra parts in the signal path.
If the source component (CD player, DAC, etc), preamp, amplifier are truly balanced then I’ve always noticed an improvement in sound quality going with balanced cabling (XLR or whatever). No matter the length. Blacker background (because the +/- phases are canceling out noise and artifacts), improved imaging, fuller sound, improved dynamics and low level detail, bass, etc.
I know many will say if it’s a short length it doesn’t matter. It will make a difference in sound quality if the entire system is fully balanced. When I discovered how big an improvement true balanced made I custom built my entire system up with true balanced components. My DAC has dual D to A chips outputting R/L +/- (which is common now days) to the fully balanced tube preamp (twice as many tubes), to a full true balanced amplifier. The amp actually doesn’t even have RCA inputs because that would take and extra tube. One side of the amplification stage (a 6SN7 into two KT150’s) is fed by the positive signal and the other half of the amp (the other 6SN7 and two KT150’s) is fed by the negative signal. After the amplification by the tubes the signal is combined at the output transformer. This is “true balanced “ circuitry.
Equipment that uses single-ended circuitry and a chip/extra tube to balance the signal typically adds no improvement to the sound.
Even in the digital domain true balancing of the DAC’s makes a quieter, improved sound quality. I remember when Mike Moffat first designed his Theta Digital DAC processor and found that creating a +/- signal in the digital domain and feeding two DAC chips per channel produced a better sounding unit. Quieter, cleaner, less digital artifacts, more dynamic, etc. Four DAC chips and quad parts all the way out produced amazing sound quality. That was when people were still saying “If it’s digital it doesn’t matter, it’s just 1’s and 0’s”. The next step he added four fiber optic isolation IC’s between the digital processing board and the DAC board (decoupling grounds, etc) which further reduced noise and digital artifacts.
Most people in audio now know, Everything Matters!
Anyway that’s my two cents.
