Confused About Relative Sonic Impact of DAC VS. Transport

"do agree that the Jolida was affecting the sound, as there was much greater consistency from one CD to the next. "
"At first, I enjoyed the increased resolution"

good high end transport designed to be more revealing and detailed
That’s meaning that there is no consistency between one cd to another and you should hear more details because good transport extract more details and resulition , bad recording cd will sound terrible and good recording will sound spectacular this is what good hi end designed to do. I think your Jolida wasn’t good enough so all your cds sounded consistent with low relatively resolution but
the ’thin’ and fatiguing sound of the Heed I suspect is because maybe this transport is not in a good synergy with your system and / or upgrading your coax and rca cables is a must and/or the Heed is not good enough transport.
I have the Simaudio 260T it’s a remarkable transport first I bought it there was nothing special after a long break-in its sound is so natural and analog I am not missing my vinyl collection anymore,.You should consider also the CEC TL5, Jay CD transport and Cyrus CD T all remarkable transport options.

@stuartk , a nice system. I agree that since you’re using the Synchromesh and Steve’s cable there shouldn't be any jitter issues. I mentioned it earlier, vibration control is important to the dac and the transport, either with footers or cones in combination with a platform. Some components respond well to mass loading. 
Power cords for digital devices have a tremendous influence on sonics. You should be auditioning different PC’s since they will impart their own sonic signature to the component. Shielded cables are preferred according to many designers.
My big question to you is, are you using a linear PS on the Synchromesh or the stock wall-wart?

And as stated by others, separate power to analogue and digital is recommended. It will help reduce the noise generated by digital devices that can contaminate the mains. I’m not sure if you’ve installed dedicated lines, but the digital sources should be on an isolated power strip or conditioner with filtering.

In my digital setup every time I swapped a PC or SPDIF cable there was a change to the SQ and timbre of the music.

It seems like you are swapping the S/PDIF coax from transport to Synchromesh. Just for kicks, try replacing the Empirical coax with a quality cable and see how this affects sonics. 

lowrider; I can certainly try that but I won't have another quality digital cable until the middle of next week. Thanks for the suggestion.

lowrider: sorry-- didn't see your question. . . I'm using the stock wall-wart.