Upgrading Opportunities 2

Like Erik I am pretty pleased with my existing system. But lately I have been looking for "upgrading opportunities" either by just tweaking, new IC's and PC's, or new electronics. My listening ranges from movie scores to rock/pop with a small dose of Jazz/Blues thrown in. The system:

Transport: Theta Data Basic II
Dac: Theta Pro Basic IIIA (both RCA and XLR outputs)
Digital Cable: Cardas AES/EBU (generation before the current Lightning)
Dac to PreAmp IC: Cardas Golden Cross RCA
PreAmp: Classe CP60
Amp: McIntosh MC300
PreAmp to Amp IC: Cardas Golden Cross XLR
Speakers: Thiel CS3.6
Speaker Cables: Cardas Golden Cross
Turntable: Denon 47F
Cartridge: Grada Sonata
Analog Pre: Lehmann Black Cube (early version)
Analog Pre to PreAmp IC: stock

My most recent purchase that made I difference was a Cardas Golden Reference PC. I have it hooked into my DAC. With the PC the upper end smooth out and filled in the midrange just a tad. I also tried it in the Amp with the same results. In the PreAmp I heard no difference. The Cardas digital cable is also new but heard no difference then with the Digital cable from Theta (RCA). Because the PC made a bigger difference I have been leaning towards replacing them all but have also thought about upgrading my IC's from Golden Cross to Golden Reference. I am just not sure the IC change will make that big a difference. I also want to change out my Denon. I can get a good buy on a Basis 1400 but any other ideas would be appreciated.

Anyway, there it is. Any comments, questions, or rude remarks are welcome. One finale thing, all electronics (except for Amp) is sitting on glass shelves on the wall with BDR Cones (#3's) between electronic and glass shelves.

Thanks for any and all advice!

Tim