advice on brightness

i just set up my first system and although the excitement hasn't worn off, i have become aware of a pronounced brightness and sibilance in the sound.

my set-up is very modest and any advice would be greatly appreciated.

-Audio Refinement Complete integrated

-Harmon Kardon dvd25 (not the best for CDs, but it does have a good DAC: Wolfson XWM8740 Delta Sigma 24-bit/192kHz, same one in Arcam CD82)

-Athena AS-B1 bookshelf speakers

-AudioQuest Type 4 speaker cables (terminated with bananas)

-Straigh Wire Symphony II interconnects

i'm hoping i can resolve the brightness with different interconnects. my budget is around $150.

thanks!

~derek