You're dealing with two pretty different presentations to begin with.
Sony's is far more dynamic than either the Oppo or Cambridge's. The reviews on the Cam and Op say as much. owning a couple Oppos, and a few Sony's, and having heard the Cam locally, it's quite eveident to me which is the more demonstrative. Sony. hands down.
Secondly you're used to one sort of sound and now are migrating away from it into a new sort of sound. one not as punchy.
third, the Cam 840 just might not be entirely run in as I've seen here online posts saying it needs upwards of a years use or from 300-400 hrs. Some folks simply won't wait or feel it's not for them prematurely and off the thing without full knowledge of it's final voice.
If I buy a CDP and find I HAVE to add a DAC for it to excel, or have some mod done to it thereafter, I've likely gotten myself the wrong CDP.
Sure, adding a better power cord (mo' $$$) can help improve the punch or slam. Adding a upscale DAC most often will increase the performance level too. ICs as well can assist but not so much as power cable exchanges will in that area of impact. together, PC & IC might fix it for you. I do know they'll help.
Lastly, on balance, your system seems as quite an easy sounding system without the Sony being in it and what you've described here. The Sony was the link that provided you the jump your whole system had... now it's not in there.
Rigs are always a mix... or a stew.
to get it back... go find another Sony with XLR...
Buy a Bel Canto DAC 3...
Add a punchier PC to your 840... and step up in your source IC too. Taipan Helix, Python Alpha, or helix, Kimber Paladium PK 10, MIT S1 or Magnum series ICs.
The cheapest way is simply to get a Sony or likewise more dunamic CDP... SCD 1's are still out there though I'd opt for a more current unit.
The least expensive way is to wait it out some more and maybe, just maybe, change your own perspective on how the music is being rendered is as good... just different.
Good luck