balanced/xlr vs. unbalanced/ single ended

would a true balanced pre/processor to amplifer (Meridian) sound measurably better than single ended/ unbalanced. all the interconnect cables are 1 meter. the speaker cables are 14 ft. for the fronts and 42 ft. to the rears. all high end/expensive cables.
Does anyone have a fully/true balanced Meridian processor/amp combo into passive speakers?
Depends on the manufacturer. Meridian believes in balanced, so they put more research into balanced systems, so their system will sound better balanaced. Musical Fidelity, however, does not believe in balanaced, and don't even offer anything besides single ended.
I just went from a SE ARC preamp to a balanced ARC preamp
to utilize the balanced inputs on my JC-1 monoblocks.

The difference is night and day-go balanced.
To my ears I am also pro , true balanced.
My friend has a Meridian 565, 508.24 and yes running fully balanced was a huge difference into the ARC D400 MkII amp to power passive speakers. If the manufactures actually designs a fully balanced piece of equipment (most are not, but the Meridian is) use it!
I have another thread in this forum about this sort of thing. But there are no answers yet so I'll hop on to this one! In general, does delivering a signal to a preamp over balanced connections wind up delivering twice the voltage to the gain stage as using RCA? I ask because I'm worried that if I go balanced with my Pass X1 I will then lose that much more usable range from my volume control.
Physics and gain and noise level difference aside I find that single end provides a more linear, fluid, laid back vs the more open and aggressive, open and in your face sound XLR cables do.
WHen Properly grounded and RCA connectors locked I think they give a superior musicality to the overall sound.
Just my very subjective observations.
I'm using a Meridian 861 and I too found a noticeable improvement with balanced cables over 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.
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

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.

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.
hey there Johnsonwu, interesting answer and I'd agree with you too, but I'd also add that I have two systems hooked up presently one being single ended and one being balanced and somehow the balanced system sounds a fair bit better. Again it's not apples to apples so a hard comparison. I think they both have their virtues overall but from what I've heard balanced seems to win the overall coherency, musicality, extension and your right power and slam to the sound but in a room that has pretty nice acoustics and room treatment along with room correction, I've found balanced superior. Mostly amp to preamp balanced, and Blu ray to preamp balanced.