Guys, thanks for the responses.
Miklorsmith, how would a Squeezebox help?
Rajacat, I've driven the XRS's with a Super T, a Sansui ss amp, Fisher 30a el84 monoblocs, a modded Harman Kardon A300 tube amp, a modded Dynaco ST70 and a Carver TMC with a variety of preamps, from a NAD to a Foreplay to an Aikido-based preamp with 5687 tubes. I recently took the speakers to a hi fi dealer here in Baltimore and tried them out with a Cayin a50t and a Rega Apollo on the front end. The results were much the same as with all the rest: mindblowing and perfect on some cds, painful on others.
The one constant has pretty much been the 5687 preamp. To my ears there is not a substantial difference when I remove the preamp.