I fourth upgrading the speakers rather than the source although I agree that the Cambridge can be a tad bright in a lean system. I've never been a fan of the Chorus line which were just not well enough balanced for my liking - a bit too much treble energy IMHO.
If you are absolutely fixed on upgrading the source, then I think you could look for something with a different sound signature to the Cambridge. You definitely don't need to throw 4k at it - have a listen to some of the tube output players around. Musical Fidelity A5 is a very smooth listen as is the Cayin CDT-17A. For non-tube players, the Marantz line (SA11 or SA15 models) are also more lush in presentation style than the Cambridge.
If you are absolutely fixed on upgrading the source, then I think you could look for something with a different sound signature to the Cambridge. You definitely don't need to throw 4k at it - have a listen to some of the tube output players around. Musical Fidelity A5 is a very smooth listen as is the Cayin CDT-17A. For non-tube players, the Marantz line (SA11 or SA15 models) are also more lush in presentation style than the Cambridge.