My answer has already been given by others, but I'll repeat it.
Go change the settings in the equalizer in your receiver: $0
Try other listening modes ("jazz", "live", "vocals", etc) and see if you like that sound better: $0
Change speakers: Cost varies.
Denon makes a very good receiver, and I doubt you are short power, so the sound is caused by your equalizer (which you can set flat if you like) and your speakers. Changing receivers won't help.
Paradigms can be a bit bright for the tastes of many. I find they are awesome HT units, but have mixed feelings on them (my experience is mostly Studio v3 range) for stereo music.
As an aside: I'd love to see the market adopt two things that don't exist now.
1) I'd like to see all speakers come with a list (better still, on a memory stick / downloadable) of EQ settings to bring them flat (this would be particularly awesome to do pre D-A conversion so as to have a basically unlimited band equlizer).
2) I'd like to see EQs have set trends for "more bright", "less bright", etc. I see these in computer audio cards, but not in home electronics. The closest I see is the surround modes "jazz", "hall", etc.