Best Digital Interface

If your transport is providing S/PDIF, it's never a good idea to convert this to USB.  The target DAC will have to re-convert back to S/PDIF and I2S anyways, but now you have timing problems since USB is really a data packet interface and not an audio/timing interface.

The RME --might-- be re-clocking the S/PDIF data, but the S/PDIF data from the Node 2 is already clocked using the sample rate of the original music data.

I believe what your original inside outside statement means is that the RME will accept an external clock signal over the SPDIF interface

The S/PDIF interface requires the data to be clocked from the source.  This is the only way it will work and it is part of the interface specification (the digital pulses representing data will need to be transmitted using the timing of the original music data, such as 44.1Khz or 96Khz, etc.)  However, there are some DACs that will re-clock those digital pulses in effort to reduce jitter and increase accuracy.  Sometimes this provides an improvement, but not always.

You may be getting confused with DAC/transport systems that use a "master clock" for S/PDIF.  In this scenario, there is a separate device that generated exactly timed "clock pulses" to BOTH the transport and dac.  The transport and DAC do their audio encoding/decoding based on the timing of the pulses from the master clock device.  This is usually a closed proprietary system which requires the transport, dac and master-clock devices to all work together.  This is an option usually on $$$$ level equipment.

Both ethernet and USB are data-packet based interfaces.  However, the actual communication protocols are different between the two.


" USB data is sent in packets Least Significant Bit (LSB) first. There are 4 main USB packet types :Token, Data, Handshake and Start of Frame. Each packet is constructed from different field types, namely SYNC, PID, Address, Data, Endpoint, CRC and EOP. The packets are then bundled into frames to create a USB message."

@phusis - you should try a Pink Faun AES/EBU card (as long as you're not running Linux on Intel cpu).  You can even get it with upgraded OCXO clocks.

I know the Marian Seraph is likely a very good card, but it's geared towards pro audio where you need a ton of digital outputs, lol.