If you did go with a preamp like the LS-15, which has SE and XLR inputs/outputs, you can always upgrade to balanced cables when the budget allows.
System advice
I'm looking to upgrade my system preamp. Right now the system mime running is a set of Martin Logan SL threes, PSE studio five monoblocks and a Superphon Basic preamp. I've been looking at mainly Audio Research and Conrad Johnson preamps, mainly because I want to go to a tube preamp and I want to go with a company that is both well-established and well reviewed. I'd like to find something that has balanced outputs as well. I'm looking at something roughly in the thousand dollar range and have been looking at the LS 15, SP nine and possibly a premier seven or premier ten. I'm using audio quest Ruby interconnects and I'm wondering if I can get these re-terminated to XLR? Any advice on a preamp purchase or information on this system in general would be greatly appreciated.