Balanced versus single ended

As with most things the devil is in the detail, I have heard both in many different guises and believe that, on its own neither makes an audible improvement, its far more about how the technology is put into practice.

A fully compliant AES 48 installation with good cables will always measure better than a non-balanced RCA installation. Regardless of line-length, noise rejection and other cable artefacts and earth separation will be better. In theory, it should sound better - in my experience it does.

Ahh another draw ! If Your system was completely dual..balanced and not, A/B testing could be done with equal length and quality cables. Perhaps then theory and measurement would have ironclad credibility. Kind of a moot point as few system components will be wired that way. So you have a system with XLR, RCA, mixed Components maybe servo control, if it’s fabulous who cares. 

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.