I also think a good pair of used AudioQuest cables would work nicely. Your best bang-for-the-buck would be a bi-wired pair of AQ Argent. However, this will probably set you back $250-$300 used. I think I paid $275 for my 5' pair. If you keep your eyes open and are patient, you might find a slightly better deal (maybe $200). In the mean time, you might want to consider a pair of AQ Indigo bi-wires for maybe $50-$75 used, while you save enough money for Argents. You should be able to turn around and sell your Indigos for what you paid for them. Argent and Indigo are the best values in that series of AQ, IMHO.
Brady
Brady