Have you had this combo in your system for a long time & are becoming more aware of the problem? Have you recently swapped in new gear?
If things just seem to be gradually degrading, try a spring cleaning. One time, I 'fixed' an emerging grain, etch and chalk by remembering to clean the interconnects/jacks/spade lugs (visible gunk on the cloth) and 'wiping' the switches (turning them on/off/on/off repeatedly). Oxidation can collect over time, even on the switches which are cleaned by 'wiping'. Very cheap fix and a good idea from time to time in any case.
I have several DACs (Theta Gen II DS Pre (pasive pre), Acurus 5.1 for HT, Oppo 981 & TaCT 2.0 RCS. I tried a few tweaks on all of these to good efect.
First, I inserted an anti-jitter interface that improved things generally (camelot 5.1 - also genesis digital lens, theta linque, etc. are good & available here at A'gon), especially in the treble.
Second, I tried the Musical Fidelity Tube Buffer. Smoother highs, more dimensionality & depth of soundstage. I run passive pre straight into solid state Levinson monblocks and so may benefit from the MFs more than someone with a traditional preamp.
Your mileage may vary.
You may also want to insert the Goldie into another system that doesn't suffer acute treblitis. You may also have a component, e.g., resistor, cap, diode, etc., that is failing and causing the Goldie to sound worse. A trip to the test bench may be in order if the sound really has changed, especailly in light of the comments by Rademaker.
Supprt your local dealer as well as A'gon. Good luck!