Balanced versus single ended

Balanced is theoretically better than SE.  Separating the ground between the 2 channels eliminates a lot of hum and crosstalk-type issues.  This doesn't mean that it will always sound better to all listeners, but it shouldn't sound worse unless there's an implementation issue.

You're never "required" to use an op amp.  Normally, that would suggest that the design is already op amp-based, or that they're using it to invert the signal at some stage to create a balanced signal.  A discrete gain stage or op amp is required to convert any SE inputs to balanced operation.  In the case of Audionet, they appear to have developed a proprietary op amp that is presumably used in all their active stages.

Balanced makes for a more reliably low noise system.  Others have noted hum, earth loops and noise can creep into single ended systems, requiring detective work to locate and rectify.

There is also talk of more gain with balanced.  As I understand it the extra 6dB is a lower noise floor rather than extra gain.  Anyhow, this is a free benefit from running balanced.

I have run my whole main system balanced for about 30 years now, from cartridge to power amp.  It is very quiet and I don't get noise problems.  There is a little additional cost on cabling, but otherwise it's a free lunch.

Very few products even have balanced connections, at least the ones I’m interested in or happen to own. I tend not to stress over it. I’m not about to change out my Amp, dac, turntable, etc...just to gain maybe a 1% difference in sound quality. However, in my back up system, which includes Naim products, it does include balanced XLR connections (2), 5si and cd5i. Luckily the cd5si already came with an XLR balanced cable in the box. Naim recommends the use of such over an RCA connection.

Pro--ject just released a new turntable, the x8, which is a fully balanced design. Additionally, they offer 2 balanced phono preamps to pair with it. However, to keep it balanced all the way through, you would have to buy an Amp with balanced line in connections, otherwise, why bother with it.

There is also talk of more gain with balanced. As I understand it the extra 6dB is a lower noise floor rather than extra gain.

That’s not correct. The extra 6 dB is the doubling of the signal amplitude due to having 2 signal wires with opposite polarity. Here’s an online calculator. Put in 1V as the start, 2 V at the end and it will come out to 6. This is the same ratio you get when going from RCA to XLR.

https://aetechron.com/calculator-Volt2dB.shtml

As others have noted, with short runs away from noise sources the noise is the same.

So, in terms of the signal to noise ratio (S/N) the N isn’t reduced, but the S is increased.

I can only say my present setup, balanced from digital source through real balanced pre, finally through monoblock amps, which are also in effect, true full balanced I get best sq.

I've also had any number of se components over the years. Certainly, I have higher resolution than systems or components that contained se. Still, without having the choice on most or present components to directly compare hard to say. Balanced does have advantage of lower noise floor, and components that are truly balanced have inherent advantages as well. Not sharing power supplies, output transformers in case of tube components, signal path circuit is only good.

In case where component is not truly balanced, I can imagine se being better, in this case balanced is add on, using transformer or some other scheme for xlr.