BNC or Coax?

Hi Everybody.

In connecting a USB converter (like a Trends 10.1 or CryoParts Pop Pulse) to a DAC, is BNC better than coax?
BNC is the only true 75 ohm connector. SPDIF is not ( if that's what you meant by coax). Therefore, BNC is always better then RCA (SPDIF) for digital transmission.
SPDIF (Sony Philips Digital InterFace if I recall) is the protocol transmitted across the cable, and is used whether the coaxial cable is terminated by RCA or BNC connectors.

The SPDIF protocol includes left and right channel audio data, flags (e.g. to indicate pre-emphasis), subcode information (e.g. track and disk/track time info), and clock.
Here is more information on the SPDIF protocol, which as Ghostrider45 indicates can be transmitted over coaxial cable that can be terminated with either RCA or BNC connectors (and can also be transmitted over optical cable):

I wanted to add, in case it proves to be relevant, that RCA-to-BNC and BNC-to-RCA adapters are readily and cheaply available, although of course it is always good practice to avoid adapters where possible:

-- Al
So, is the concensus that RCA termination or BNC termination is equally reliable for transmission of digital audio (say between transport and DAC)??? Or are there quantifiable differences between the two type of connectors?