How to proceed?

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..

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

I wasn’t actually looking for more resolution. I’m much more a music lover who prizes emotional engagement.

I already know that already...😊

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 ...Anyway it was my case in the past...

I dont understand why the Lokius will not work in improving it ... For me then it is a problem about the speakers/room relation ...Of a bad synergy between a good dac and the rest of the gear interaction ...

I dont think that buying more costlier EQ will work better than this basic good one for sibilance...

In general looking for more resolution is not always the best way, sibilance may invite itself by exagerated high frequencies band coming from bad synergy or from a bad choice in some design ...I myself always asked for more musicality and more clear spatial localization acoustic qualities first, never for more resolving qualities first, because i hate fatiguing sounds ...My two systems dont lack details at all but they are never in my face ...They are there waiting for my attention ...

Borrow another dac...

@mahgister

A Schiit Lokius didn’t help but perhaps a unit with more bands????

I am not an expert here at all...

Once said i experienced sibilance  when i had bad synergy between gear pieces speakers and dac or amplifier  or bad dac( which is not the case here i think) and room acoustic can only solve it in part ....Room acoustic alone  dont solve synergy problem ... A bit of EQ can help a lot ...