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

 I asked AI about Merason’s implementation of the Amanero USB card, and received this:

 Merason incorporates the Amanero board but surrounds it with proprietary, high-performance circuits rather than using a standard stock board implementation. 

• Advanced Galvanic Isolation (Capacitive): While the Amanero board itself manages USB audio data, Merason adds a dedicated capacitive isolator module to isolate the I2S signal from the USB card before it reaches the Burr Brown DAC chips. This ensures that noise from the computer or the USB transceiver card itself is not transmitted to the analog stages, a critical step often missed in stock implementations.
• Low-Jitter Clocking Strategy: The USB input is engineered to deliver a low-jitter I2S signal. The design employs two precise oscillators specifically tuned to manage multiples of 44.1 kHz and 48 kHz, which allows the DAC to precisely match the incoming sampling rate and minimize jitter.
• Dedicated Power Supply: Merason does not rely on the 5V power from the USB connection, which is typically noisy. The DAC1 Mk II includes a sophisticated, linear power supply with twelve separate supplies, with dedicated, oversized transformer sections for various components to keep the digital input section fully isolated from the sensitive analog output stage.
• Signal Path Refinement: The USB module outputs an I2S signal that is carefully shielded to reduce electromagnetic interference, contributing to the "blacker" background and improved resolution described by reviewers. 

Key Differences from Stock Amanero Combo 384/768

While the Combo 384 is a high-quality, popular interface (known for its musicality), it can produce significant noise in its stock state without proper isolation. 

• Vs. Stock Combo 384: The stock card is often powered directly by the USB bus (noisy) and may not be properly galvanically isolated from the DAC's analog section. Merason solves this with dedicated linear power and capacitive isolation.
• Vs. Stock Combo 768: While the 768 is a newer card, the Merason DAC1 Mk II focuses on the quality of the signal path and power rather than higher sampling rates. The DAC1 Mk II deliberately caps performance at 24/192 (PCM only) to prioritize sound quality over high-resolution specs, avoiding the "cold" sound often associated with some modern, faster DAC implementations. 

Summary of Improvements

1. Isolation: Capacitive isolation removes USB/computer noise.
2. Clocking: Two precise, dedicated oscillators for clock stability.
3. Power: Clean, separate, oversized linear power supplies.
4. Signal Integrity: Optimized PCB layout to reduce noise and interference. 

If you are looking to understand how these improvements sound, I can explain how the Burr Brown 1794A DACs or the discrete class-A output stage contribute to the overall musical, warm, and highly detailed sound of the DAC1 Mk II. 

@maprik if you figured out what improvements you’re looking for with your digital may be it’s worth its own topic. I know we all have our ways, but I’m not a fan of adding boxes to achieve a questionable change. 
My DAC has a built in network card and that’s what I’m using. I do not miss my streamer with the headache around power cords, usb cables, etc. 

According to Ed Meitner who designed my DAC, the best way to implement the clock is closest to the signal path. I believe that is accurate based on what I’m hearing. 

I would not waste money on more boxes. Buy more good vinyl instead. 

i understand ai can hear up to 50 khz, so you know you can fully trust it -- like 100% certain -- when it tells you what’ll happen in your system if you try a ddc...  

@mitch2  This AI description appears to be a mix of Mk I and Mk II. Whereas the Mk I USB card has the appearance of an off-the-shelf Amanero card, the Mk II does not. The important takeaway for Merason DAC owners is the Mk I and Mk II are not the same, and improvred USB performance appears to be a differentiating feature between the original version and its successor.

All of this is academic to some degree regardless, as a galvanically isolated USB receiver is certainly advantageous, but not a panacea in itself. Galvanic isolation performance varies with individual architecture and DACs with galvanically isolated USB routinely respond favorably to outboard USB isolators/regenerators. 

@ted_b - It appears you are correct. The USB input (and many other aspects) of the Mk II that I have was significantly upgraded over the MkI owned by the OP. Improvements affecting the USB input included capacitive galvanic isolation, precision oscillators for low-jitter, more through-hole components for shorter conductor paths and lower USB input signal losses, and PCB layout changes to reduce impedance and improve power delivery.

What I am hearing through USB is likely quite different (i.e., improved) from what the OP would hear, which is another reason that, IMO, the OP's money would be better spent on the upgrade than on chasing improvements due to input changes through a DDC. 

I have been very impressed with the Merason house sound signature and suspect it has much to do with their purposely optimized implementation of the Burr Brown PCM1794 DAC chips that use BB's (purchased by TI) advanced segment architecture which, to my understanding, is sort of a hybrid between multibit (ladder) and delta-sigma technologies. 

I have long used R2R DACs (my other DAC currently is an Aries Cerat Helene, an R2R design using multiple AD 1865 chips) and I find Merason's presentation a nice balance between the musical, natural, full-bodied, and tonally rich sound I enjoy from R2R DACs and the more precise and extended delta-sigma sound.  The Helene plays more grandiose and muscular but, when I am listening to the Merason the sound is close enough that I do not miss those qualities.  I just took the DDC out of the path and reinstalled my USB input directly from my Sonore streamer (using a Cardas High-Speed Serial Buss USB cable) and I perceive a bit more clarity and energy, without losing any of the musical qualities I enjoy. I am actually looking into the DAC2 upgrade, or possibly Merason's new Mountain DAC that I would use to replace both the DAC 1 MkII and the Helene.