Just got a new power amp

Can someone discuss the pros and cons of 'op amps' that ? must convert balanced signals to single ended signals?  It is my understanding some equipment thus sounds better with single ended cables vs balanced cables.

Hey @fastfreight

When an amp or preamp has XLR inputs there are three things that may be done: 

1. Ground one signal pin.  
2. Use a transformer to convert to single ended
3. Use op amps in differential configuration
4. Very very rare - use discrete circuits to convert

The first case looses any noise / long distance benefits of the XLR cables.  The connector is a convenience feature.    The second is fully discrete but subject to bandwidth and distortion limitations of the transformers, may add character all its own.  Third is the most common and I’m sure you don’t even know how many times that was used in creating the music you listen to.  

Professional devices, from microphone preamps to mixing boards and tape recorders almost all rely on op amps as the inputs and convert the signal from differential to single ended before doing whatever they will do with them, so keep that in mind when evaluating whether this is good enough for you.  

Like any active devices they may add noise or distortion, but it is only at the end of the chain that Audiophiles become obsessed with them! 

I would not say they have any specific sound by themselves or their use, so it IS good to test with them.  Also, while XLR is "professional grade" and bigger and more complicated there’s no guarantee at all in a home away from radio towers and machinery that you’ll ever hear a difference.  If you have a long run to a subwoofer, or to active speakers in your surrounds you might as well go with XLRs to ensure the least likelihood of noise pick up though. 

PS Audio's Paul McGowan recommends to use XLR when that is an option and indicates that virtually all their equipment is true balanced.  Makes sense to follow manufacturers recommendation.  He has a number of youtube videos on the topic, one is referenced below.  

https://www.youtube.com/watch?v=PzEmKPTb18g

Besides the 6db of gain,  you MIGHT have a quieter signal from your preamp to amps withe XLR.  Years ago I had a system that was crazy sensitive.  Some of the issues were from the built in phono preamp, and XLR IC’s did help. Since then, I’ve haven’t gone longer than 3 meters between my preamp and amps and in my current home, with my current system, RCA’s have worked just fine.

All the best.

I do know Audionet recommends single ended interconnects to avoid op amps.

Thanks Eric.