Balanced vs RCA preamps

@inagroove noted:

"With that said, both boxes have single-ended connections as well to appeal to a broader marked.  Why? Many sources are single-ended (ex. my Zest phono-pre is single ended output only, so the cable going into the ARC line-pre must be single ended)."

Another reason for RCA and fully balanced XLR outputs might be for subwoofers. If the two sets of output jacks (XLR and RCA, respectively) are in parallel- meaning they both output the same audio signal, they can be used for connection to multiple amplifiers or an amplifier and a pair of mono subwoofers. My XLR outputs can connect to my amps XLR inputs and RCS outputs to my pair of subs.

Another reason for RCA and fully balanced XLR outputs might be for subwoofers. If the two sets of output jacks (XLR and RCA, respectively) are in parallel- meaning they both output the same audio signal, they can be used for connection to multiple amplifiers or an amplifier and a pair of mono subwoofers. My XLR outputs can connect to my amps XLR inputs and RCS outputs to my pair of subs.

I am not running my sub at the moment; however that's the way i ran it out of my SLP 05.  I used the balanced in from my Marantz SA10 and the balanced out to my Cary V-12 and ran the sub from the RCAs out of my SLP05.  The quality of the sub I was using left a lot to be desired, but it worked fine.

@Jpan Could be.... but it's true.

A word of caution. Just because there’s an XLR connection does not mean it is a truly balanced circuit. I’ve seen many implementations where it’s actually a single ended circuit transmitted via XLR connectors. 

@jpan , if the manufacturer clearly states that a piece of gear is truly balanced, I am willing to take his word for it.

If your preamp is not balanced, it might start sliding and fall of the shelf so I would always go with a balanced one