I can't speak the the I2S issues raised by the OP, but with regard to the AES/EBU interface being limited to 192khz/24 bits, that is because that is the limit according to the AES/EBU specification. Due to this limit, Dual AES was developed to support higher resolutions. While you can of course bypass this limitation by using USB, some DACs seem to perform better with AES. At least, that has been my experience, using an Aurender N20 with a dCS Bartok.
Aurender
I have a Korean car, watch KDramas and even listen to some KPop, but I don’t get what Aurender is doing.
I’m currently in digital hold given that my new Holo DAC died, but intend on listening to my IFi Zen stream and look at upgrade paths.
Some of the most respected members of this forum swear by Aurender, so it must deliver, but here is my point of confusion:
1. Coax and AES are the preferred outputs, but higher bandwidths require dual AES out, but I don’t have dual in on my DAC.
2. Aurender’s top models claim to have great clocks, so why not pass this on to the DAC via I2s?
3. Top Aurenders accept external clocks and I assume this is used with a DAC that accepts external clocks, but why bother when I2s would take care of this?
4. The argument against I2s is that there isn’t a standard, but this isn’t a problem in most implementations.
I’m sure that I have misrepresented things above, so please correct my understanding.