Exploring Preamp options for the Pass XA25


Please feel free to share preamp options for the XA25. I presently have an Acoustic Research LS-3 and am not sure this is the perfect combination. The Pass Headphone preamp is one option that I'm considering. Tube preamps?
128x128coachpoconnor
The Backert Rhumba is a splendid match with my XA-25. I get pretty much the same sonic qualities as wlutke above with his Herron. The XA-25 is a great match with tubed preamplifiers, IMO!
I have the PS audio bhk pre with my FirstWatt J2. Sounds great. However, I may seek out a Pass pre after new year. 
These are my list of recommendations so far.
Pass Labs XPA-1
Pass Labs XP-10
Herron VTSP-360
PS audio BHK
Backert Rhumba
Would any of the Prima Luna preamps be an option?

The Pass Labs are balanced. If you really want to take advantage of what it does (its distortion will be lower if provided with a balanced source), a balanced preamp is the better choice. What sort of budget do you have?