From the Pass Labs XA-60.5 manual:
So, according to Pass Labs, utilizing the balanced inputs generally gives a lower noise floor (as has been discussed already), and slightly less distortion ("slightly less distortion" is not defined by specs in the manual).
Having tried both balanced and single ended operation on my XA-60.5, I preferred balanced, but using single ended did not produce an appreciable difference in sound other than an audible 6db reduction in gain.
There are many different personalities among audiophiles. Some would certainly claim a jaw dropping improvement when running Pass Labs amps balanced. I would characterize the difference as marginal.
The question comes up all the time – are balanced inputs (XLR) better than single-ended (RCA)? The answer is that balanced lines generally give lower noise and slightly less distortion. They are recommended unless your favorite source component has only RCA outputs.
So, according to Pass Labs, utilizing the balanced inputs generally gives a lower noise floor (as has been discussed already), and slightly less distortion ("slightly less distortion" is not defined by specs in the manual).
Having tried both balanced and single ended operation on my XA-60.5, I preferred balanced, but using single ended did not produce an appreciable difference in sound other than an audible 6db reduction in gain.
There are many different personalities among audiophiles. Some would certainly claim a jaw dropping improvement when running Pass Labs amps balanced. I would characterize the difference as marginal.