Single ended vs. XLR Connection Advise Needed

Caes in point. The Theta Miles ballanced version was far more better then the single ended, this had to do with the 2 dacs per channel out on the XLR path

True of course, but according to Hgeifman's post, that is not the point here IMHO.

In my experience, balanced IC's gain a progressive advantage over SE's as the length of run increases. This makes intuitive sense, since longer runs are more susceptable to RF interference, etc. At runs of 1-2m in a quality system, differences can be very subtle.

If your equipment have both outs/ins XLR and RCA more-likely it's not balanced. The true-balanced equipment has only balanced outs and that where it makse the point and sence. There has to be an output transformer present that separates positive and negative signals onto different signal wires. If you open up the cover you will realize whether the equipment balanced or not.
I always prefere the equipment that has either one of... instead of having both.

See the similar thread in the cables area, but XLR is a connector, it is not the same as "balanced." You can use an XLR connector for a balanced signal connection.

The benefit to a balanced send and receive is a very high imunity to noise and hum from sources external to the cable. This is due to the CMRR (common mode rejection ratio) being high for most balanced input circuits (including transformers). If you do NOT have a true balanced input circuit you get little benefit from a balanced cable.

The other part potential benefit of the typical (not all) balanced line is that it is set up for low Z (600ohm nominal), which makes it much easier to have long runs of signal without degredation. The actual cable plays *less* of a role than with high Z single ended runs.

The kicker is that equipment that has both "RCA" and "XLR" outputs *often* use different circuits as the output/input driver(s) for each - so the sound is not identical due to the differences in circuitry. It is impossible to predict which circuit will be superior sonically - of course there is physically more complexity to the balanced output design when implemented with active circuits (as opposed to a simple transformer, but then you get a transformer!). Some folks prefer simplicity over complexity for the sonic results. Ymmv.

_-_-bear