To DDC or not to DDC. That is the question.

Understanding the quality of USB implementation In your streamer and DAC, as well as the quality of the clock in the DAC that’s responsible for timing the USB signal is step one. If your DAC clock is not the best quality, DDC with a top notch clock (i.e. OCXO) would make the most sense to convert USB from streamer to AES or Coax to feed the DAC. If you’re simply reclocking USB in to USB out, there may be sound improvements, once again only if the clock in the DDC is better than the one in the DAC and DDC has better USB out isolation than your streamer. 
The cost of implementing a DDC adds up quickly. 
You have to purchase a DDC that would supersede the quality of the clock in your DAC, plus additional USB cable or additional AES cable if you’re going to run USB to AES conversion, a quality power cord for the clock, plus it takes up additional shelf space.

As @soix stated, and as everything in this hobby, you won’t know until you try. But considering the cost involved, you have other options for DACs and streamers, even as a one box solution that would most likely improve on your current set up. 

@johnnotkathi 

Worth watching….
 

https://youtu.be/wiU_15NpUn4?si=gaKwY3JsXG0m15It

I watched.  He is right about many factors.  However, I do not agree with him about his assertion that if you need an external re-clocker, then your DAC is broken by design.

State of the art DACs, such as the Berkeley Audio Design, Alpha Reference DAC Series 3, and the Wadax ultra elite DAC, both benefit from a high-end re-clocker.

Just to add a small note on the Merason DAC1 Mk II USB input, as I’ve looked into this a bit out of personal interest.

It’s my understanding that while it builds on Amanero technology, the implementation isn’t a standard off-the-shelf Amanero module, but a modified design with its own clocking and galvanic isolation.

So some generalizations about typical Amanero-based inputs might not fully apply here.

Just mentioning it for completeness.

From what I’ve read the Merason DAC is built with the USB connection as primary which takes advantage of Asynchronous USB. Its made in Switzerland (think excellent watches and clocks) and at around $6,000 retail they put a lot of attention on the isolated crystal oscillators. The USB input is galvanically isolated, as you’d expect. I think its designed to minimize the effect of the quality of source data. That’s the main reason for my origInal question which I meant to be Merason specific. In theory, I don’t think a DDC is needed, but as we know, audio is not about theory. I could try a DDC but I also get @audphile1. Would a <$2000 DDC beat the Merason’s clocks? Doubtful from what I read about Merason. 

You might try a conversation with AI, by asking about different scenarios related to your specific equipment.  I occasionally find some holes in the output but in general I learn quite a bit and find it to be more accurate than not.  I was curious about DDCs and asked Google AI mode about three of them with respect to my specific streamer (Sonore Signature Rendu SE Deluxe optical), DAC (Merason DAC 1 MkII), and my use of a linear power supply to power the supercapacitors in the Singxer SU-6.  Here is a short summary of the output:

• Your Singxer SU-6 (especially with the external LPS) is likely very "clean," but it can lean toward a "technical" or "dry" presentation
• Moving to the Berkeley will make your system feel more sophisticated and organic
• Moving to the Gaia will make your system feel more muscular and grand.