balanced/xlr vs. unbalanced/ single ended

If you really want to take advantage of balanced line operation, consider shortening you speaker cables (as short as you can make them) and then run long balanced interconnects.

If your setup in fact properly supports balanced line operation, the length and quality of the cables will have little bearing on the sound. The balanced line system was in fact created for eliminating interconnect cable problems and differences, as every audiophile can (knowingly or not) attest too: all recordings incorporate their use.

unfortunatley my cable length in this HT are givens, but I do agree that short length speaker cables are the way to go if possible. Anyway, I have chosen the balanced approach in both my HT and 2 channel and couldn't be happier.
Happy Listening!!!

Audio Research LS25 MKII preamp to Audio Research VT200 or D400 MKII power amps sounds significantly/dramaticly better connected with balanced/xlr cables vs. unbalanced/RCA.

Tonyptony
Balanced has about a 6 db higher gain than single ended in most cases.
It can limit both your upper and lower volume ranges. I had a Pass Alpha P in balanced mode to 2 Moon W-6 mono amps. With gain dials set to minimum and the volume just off 0, it was just a little too high of a minimum volume for my taste and the maximum volume was around 4 O’clock.
I do not have any problems with my ARC Ref3, it handles all volumes ranges, my usual volume setting is 40 and that on the Pass was about 1.5

Jwt
I also have a problem now with my Meridian G68AXV. When in calibrate I must setup the system at 85db cause I cannot get the test tone lower than 80 DB for the front speakers. So I just do 85 db all around instead of 75 db.
I do think that the efficiency of your speaker, wattage and input sensitivity of your amps also come in to play.
I do agree with most here and that balanced is the way to go, it just sounds cleaner and more open to me.

IMHO

Extremely long interconnect lengths (to the preamp or mixing console, for example) is what balanced connections are for.
Unbalanced connections over long distances will pick up hum and noise.

Balanced connections are generally for large venues such as concerts or PA systems. Home systems rarely require it.
There's no sonic advantage, per se, to balanced connections.