Cause of Muddled Middle?

I would like to have better separation in the mid-range.

I feel like things are muddled while listening to a variety of CDs.

Is there anything obvious wrong with what I have? Here's the list:

Rotel RCD-1072 CD Player
Adcom GFP-750 Preamp
Rotel RB-1070 Amp
Audio Concepts Opal speakers
CAT Cables silver RCA interconnects
DH Labs Quick Silver Q-10 speaker cables