How old is your Aqua? Chances are it won’t change too much but most times I’ve found DACs do change after 400-500 hours run time (though in my case they usually got a bit more detailed). But if it’s new you may want to run it constantly for a few days just to see if anything changes. If I recall correctly I think in one review of the La Voce the reviewer found it a bit strident on the top end compared to some other DACs. I know you said you didn’t want brand recommendations but you may want to look at Mojo audio DACs based on what you said about the Hegel vs the Aqua DAC. They have nice organic tone but are not rough on top at all, and mine sounded best when run from a good transport.
How to proceed?
Removing my Aqua La Voce dac from my system has eliminated fatigue and reduced but not fully eliminated sibilance. Running my Jay’s CDT2MKIII into my Hegel H390’s onboard dac is definitely a more relaxed presentation but tonally leaner than I prefer. Some have suggested I swap out the Hegel, but first I’d like to try another dac.
What I’m unclear about is how to go about choosing another dac that will not duplicate the same drawbacks I’ve experienced with the Aqua. Are there details in the design or specs that can guide me in this regard? I'm unsure how to proceed.