Balanced versus single ended

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.

The issue goes beyond simply the use of different cables as the "standard for balanced line operation" that Ralph often discusses focuses on how audio equipment is designed with respect to grounding and shielding as discussed here.

Could there be sonic differences based solely on whether the equipment is designed to be balanced or single-ended, probably, but how that single difference would affect the sound we hear is something I couldn't predict.  If implemented properly, the balanced gear should be have less noise.  However, it has not been my experience that fully balanced equipment is immune to all facets of IC cable design such as wire gauge, geometry, shielding, connectors, and materials,  but then IME most cable changes are subtle not revelatory, so YMMV.

Certainly, long runs, if equipment offers, use XLR to protect from the added potential of problem(s). But, even a long run at home, really not the same need as a swarm of this and that in commercial setups.

Short runs, home audio system, why?

One clear advantage is the snap in locking connector. 

For stable matched secure contacts for L and R, I changed all my interconnects to locking rca connectors, and use XLR/RCA from my Sony CD player's XLR out, just to compare. I cannot hear any difference between it's XLR out or it's RCA out.

I don't really have a strong opinion in an otherwise well functioning home whether you go with XLR or RCA, but I will say that if you build your own, Neutrik has silver contact XLR's and Parts Connexion has a line of pure silver, balanced IC cables you can combine to make outstanding / end game interconnects for a lot cheaper than you'd buy.

I humbly submit that it really depends on the design of the preamp and amp. But that is just from my own experience and without any engineering background. It always surprises me that so many reviewers claim that SE is just as good, and how many reviewers seem to keep only SE IC's on hand. 

As an owner of an ARC Ref 6 and Ref 80S and Ref 150 SE I know that Warren Gehl and Co strongly suggest running balanced with the very best IC's you can afford. I conducted listening tests with a wide assortment of balanced IC's at all price ranges and heard huge differences. I settled on Cardas Clear Beyond.