Very difficult to troubleshoot from afar. I suggest you contact your GoldenEar dealer and have them come to your home and help identify the issues. Certainly all of your equipment seems very high fidelity.
If I was to make a guess, it sounds like a room issue to me. "One-note" bass, as you describe, is almost always associated with a room node(s). And lack of bass will make the system seem bright and more forward. Experimenting with room placement is one way to help identify if this is the problem. We recommend a wide placement, significant toe-in and at least a foot or more away from walls.
The unusual thing is this is not something that should have changed, unless you changed room locations. Since you have only one source, the "try a different source" as a starting point suggestion in the process of elimination would require hooking something else up to the system. But all components should be ruled out one by one.
It is also worth noting that the Tritons are in the middle of their break in period and perhaps they will change again in the next 30 hours. I can tell you that "bright" and "lack of bass" are not something we hear about the Tritons
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Regarding specific tracks, we all have our favorites - what you're used to is always a good choice. Bass level setting is a room and person specific adjustment, but it seems everyone is happy with settings between 9:00 and 12:00 on the dial.
Hope this helps - if not, enlist the help of your GoldenEar dealer.