XLR/Balanced problems???

I'm using a Pass Aleph 3 amp, Pass Aleph P preamp, a Studer(revox)A727 CD(professional model), Cardas Quadlink speaker cable, Mission 753 speakers, and both balanced and unbalanced Cardas Cross interconnects. I'be been using the variable output on the CD with unbalanced Cardas Cross and the sound has been a little bass shy, but fine(even with the CD volume at maximum...and I know Aleph 3's aren't bass heavy amps). I recently started using balanced Cardas Cross cables from the CD to the pre-amp. The signal is much louder, and the bass is much stronger...so much that it distorts a bit(especially noticable on vocals). Is this natural? Is my problem with the speakers(I've never had the problem before), or should I forget about using balanced interconnects?