How to proceed?

@blackbag20 

Thanks for your comments. If the sibilance had occurred at a point when I hadn't just replaced two components, I might well call Aqua but it seems highly unlikely to me that what I'm contending with currently is due to a fault in the dac. 

Yes; it's encouraging to receive responses, especially from guys who not only have the expertise but the patience and generosity to stick with me through the entire problem-solving process. 

We are an aqua dealer used to sell hegel as well

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@audiotroy 

Thanks for your comments. I'm a physical media guy.

If I could afford the Aqua Diva, I would buy it in a heartbeat!  

@stuartk hey there, I was looking back at some old threads in 2019 where you, grannyring, and a few others were going back and forth about the S2, S3, possible upgrades, and comparing and the upgraded MHDT Labs Orchid as a reference point. It gives a reference point, I had a nicely upgraded MHDT Orchid myself (for years) and used all the same tubes grannyring did. I noted you were commenting the same types of things back then about not wanting extra resolution or detail. I found this thread and banter kind of interesting.

https://forum.audiogon.com/posts/1794473

S2: There are other threads indicating the characteristics of the S2 version dac as being "warm" in fact. It does strike a thought that your upcoming cable swap test along with swapping other components in/out one-by-one might reveal something more. And finally other area comes to mind.

One other thought - apologize if this was touched on prior, somewhere. I was looking up the design of the dac and its care to isolated boards and power supplies within the design itself. Not sure about the Hegel, but worth asking anyhow...

AC Power:

AC wise, what is your Hegel amp and Aqua DAC plugged into at this time? By chance was anything changed where everything was plugged into (plug locations, power cords) after adding the two new major components into your system? Have the particular AC wall sockets been checked by an electrician for added noise, by chance? Something else to check if you have not already done so, fwtw.  

@decooney

hey there, I was looking back at some old threads in 2019 where you, grannyring, and a few others were going back and forth about the S2, S3...

Thanks for your research on my behalf! I’d forgotten all about that thread. Looking back I see why I opted to stick with S2 -- I was unwilling to surrender the S2’s "warm and organic"quality for the sake of detail. My system is considerably more resolving now than it was back then, so I feel the same way.

One other thought - apologize if this was touched on prior, somewhere. I was looking up the design of the dac and its care to isolated boards and power supplies within the design itself. Not sure about the Hegel, but worth asking anyhow...

Given that Hegel’s claim to fame is ensuring the amp does not degrade the signal between input and output, I’d be surprised if they neglected isolation but I’m no engineer. I do recall from reviews that the H590’s dac board is much better isolated than that in the H390.

AC wise, what is your Hegel amp and Aqua DAC plugged into at this time? By chance was anything changed where everything was plugged into (plug locations, power cords) after adding the two new major components into your system? Have the particular AC wall sockets been checked by an electrician for added noise, by chance? Something else to check if you have not already done so, fwtw.

Amp and dac are plugged into some sort of "audiophile receptacle" (don’t recall brand). It’s not filtered, though. The transport is plugged into a standard receptacle. I had my electrician check connections to both last year and he said they were fine, FWTW. Nothing has been changed since Hegel and Jay’s were brought into system. I’ve received very conflicting advice regarding power treatment. I know that Hegel advises against such measures for their integrateds.

This is embarrassing but it just occurred to me that I may have neglected to mention the AC cords I’m using have the same wire as the IC’s -- copper + silver-plated copper! Sorry about that. Swapping them out for some Audio Art all-copper cords didn’t make a discernible difference but that doesn’t mean that some other all copper AC cord wouldn’t yield improvement. Whether it would make more sense to upgrade the cables or plug the existing cables into a conditioner, I have no idea. I can’t afford to do both, at this point.