Just got a new power amp

I think two things are going on.  First, Paul McGowen at PS Audio has always been a fan of using balanced cabling over single ended. Second, and probably the most important reason, is that the S300 is a fully balanced design.  If you use RCA's, then the input has to be converted to a balanced signal first.  Thus adding another layer to the circuit.  

I currently have a S300 amp with the PS Audio Gain Cell preamp in a secondary system.  When I got those two pieces, I did a comparison between using a balanced cable and RCA's (both were Audioquest Columbia's) and the balanced cable did sound better.  Not by much, but it is tighter in the treble and midrange driving my Martin Logan electrostatics.

- Jeff

When single ended rca is compared to balanced XLR, how many people are actually taking voltage measurements to level match each one?

I would guess that most either don't try and match it or do it by ear.  When I tested it, I used a SPL meter and a white noise test tone.  Not exact, but very, very close.

PS Audio S300 is not fully balanced. "Bridged" output might suggest that, but it isn't a bridge of two amps but 4 Mosfet bridge to flip speaker direction between V+ and GND, since output is single voltage supplied.  Some class D modules, like Hypex, use dual +/- supply and only 2 output Mosfets.  S300 is based on 300AS1 Icepower module, almost identical to 200ASC (in my Rowland 102), but  with stronger output Mosfets.  Both my amps Benchmark AHB2 and Rowland 102  don't have RCA inputs.  

The most important thing is what you can hear.  Some features of XLR, like higher noise rejection or locking connectors with female input side (pins recessed - not exposed) might be very important in a large studio - not so much at home.

PS: Both speaker terminals have about 30V DC (half of supply) on them - do not short  either to GND.

 

kijanki

PS Audio S300 is not fully balanced ...

You might want to check the specs of the amplifier here. They certainly reflect those of a balanced amp.