How to proceed?

Here we must ask for experienced people not for logic 😊...And i am not an audio engineer for sure... Myself i will try an other dac to begin with, any other one to see if the problem stay with me ,  ...Synergy is always a three partners affair mainly, dac- amp- speakers, where one is the main culprit ...

But more experienced people here will advise you perhaps better ...

@mahgister

I only say that the dac may not be the problem in itself but the synergy on some frequencies response never mind if it is very good on some other aspects between it and the rest of gear

If this is true, then would logic suggest swapping out only one component at the time (DAC, Amp or Transport) might not be sufficient -- that I might have to try multiple combinations of components? I ask this because you are better at logic ! ;o)

@mahgister 

Alright. I will start with a different DAC and see what occurs...

Borrow or buy a cheap low cost one to do the experiment and of different type than your actual one ...You will know if it is the dac synergy... Bad Synergy can exist also between high cost well designed components ...

@mahgister

Alright. I will start with a different DAC and see what occurs..

If all of your components and cables were chosen for their reputation of being highly detailed the presentation can lean too far in that direction. The leading edges of instruments and vocals are a little over emphasized and sibilance happens. A warmer cable in the mix might eliminate that and restore the balance. WireWorld and Cardas come to mind if you decide to try.The silver coated cable you're using might too much used throughout.

@jtcf

Resolution has never been a top priority. I don’t mean to be contentious but did you not read through the thread?

I wasn’t actually looking for more resolution. I’m much more a music lover who prizes emotional engagement. I was looking to correct the poorly-controlled bass I was getting in my previous system, which I found distracting and increasingly dissatisfying. Hegel amps are known for their high damping factor and the H390 has not only brought much better bass control but the speakers have come to come to life in a way that made me question whether I’d ever heard what they could do, before bringing in the Hegel

My IC and power cables are a mix of copper and silver-plated copper, chosen after finding all copper too dark and all silver too bright. My digital cable was described as having "a very liquid warmth that’s more gold than silver" in an Audio Bacon shoot-out among eleven contenders.

I’m not opposed to trying a different cable but I’d be surprised if swapping out a cable would have the same impact that results from removing the Aqua DAC from the system. The same coax BNC is used in both scenarios. When it connects transport to integrated’s internal DAC, fatigue disappears and sibilance is noticeably less exaggerated.