what 384/768 USB to SPDIF converters are available?

[Superdad]

Hi David:

The Singxer SU-6 is well-liked and can output 24/384 via S/PDIF.

https://shenzhenaudio.com/products/singxer-su-6-xmos-xu208-cpld-femtosecond-clock-usb-digital-interface

You won’t find any devices doing 768 over single BNC.

[Superdad]

14 minutes ago, davide256 said:

...which leaves me wondering if there is a good DDC that supports 768 over I2S output?

 

Actually it turns out that the Singxer SU-2 (but not the more expensive SU-6) does support 768 (and DSD1024) over I2S. 

https://www.kitsunehifi.com/product/singxer-su-2-dsd1024-usb-digital-interface-femto-second-clock-interface/

Pretty good clocks (plus support for external 10MHz reference), digital isolators, and even lends itself to conversion to use of a high-end external LPS.