Anybody use a single ended component with one that is balanced?

The OP is talking about running the XL output from the pre into the RCA input of the amp.  That will produce sound.  It may not be optimal.  

OP should use the RCA outputs on the preamp if it has them.  Or use a Henry Engineering Matchbox or a Tascam adapter. 

Oh OK. Yes, just use the RCA (aka "single-ended") connection from the pre-out to the amp in. Don’t use the XLR outputs on the preamp until you have an amp with XLR inputs. You won’t get optimal sound by just using the jack adapters - or at least that is a possible risk.

BTW: I like the XLR adapters because they always connect ground first, so they can be swapped live.  I built a patch bay to switch between preamps and amps with neutrik jacks. Better than a HT bypass! 

I think the point is that just using physical/passive jack adapters  - whether dongles or cables -- has the potential to produce suboptimal sound depending on the topology of the units.  It's not always the case but it can be.  

Better to use same jack type on both output and input, or to use an active conversion process like in the Tascam LA-40.  I know, I know, it's not in the pantheon of classic Rated A components but it really does not impact the sound...it simply allows me to use balanced for a long run between my preamp and active crossover in my bi-amped system.