XLR interconnects

on another point.....I noticed that the sound of dif. bal. interconnections have far less sound differences in the many brands that are offered...

Agree stringreen. XLR's can sound good on a reasonable budget, whereas you have to up the budget substantially more to get to a similiar performance from RCA's.

(https://www.presonus.com/news/articles/balanced-unbalanced) Some fully balanced devices(like my BAT VK-D5) will output twice the voltage with their balanced connection, and will also vary impedances, which may sound much different than their single-ended connection, depending on things like whether the device being fed’s input is truly differential, it’s impedance, etc. Here’s an article that notes some of the variables, in it’s measurements/comments: (http://www.stereophile.com/content/balanced-audio-technology-vk-d5-cd-player-measurements#MxCpgkJ7CX...) Keep in mind, if both devices are fully differential, more voltage/headroom=louder=sounds better to the ear, and may actually measure better(freq response), in some cases.

" Effort?  What effort?

XLR is the default.  Just do it! "

The effort for buying new cables for a system that's not balanced. And if the components are single ended, op amps are used to accommodate the cables, and can actually degrade sound quality. The money is better spent elsewhere.

" Reason I ask is that I will be getting a preamp that has XLR outputs and would consider using them if it truly makes a difference in sound over unbalanced. If not, then I'll stick with unbalanced cables and just enjoy the music."

Again, having components with xlr inputs and outputs, does not mean its balanced. Its not a small percentage either. Over 50% of xlr components fall into the single ended category. List some of the preamps you're looking at and I'll show you how to tell the difference.