AES/EBU or BNC port?

On a new (non DS) dac for my living room system, it looks like I’ll have a spot for another input, in addition to s/pdif, USB, Toslink, and unbalanced RCA. I’ve never used AES/EBU or BNC and am really quite ignorant about them (I currently use RCA S/PDIF and HDMI/I2S between Oppo and dac). Thinking about the future, that great unknown of potential components, which do you think might be the better choice, i.e., potentially more useful? I should mention that I don’t currently have a server or streamer. Thanks,

S/PDIF is a format that’s used for TOSLink and unbalanced 75 Ohm coax (often with RCA connectors but sometimes with the more technically correct BNC connectors)
AES3 (which used to be AES/EBU) is a very similar format but is designed for balanced 110 Ohm and usually has XLR connectors.
https://en.wikipedia.org/wiki/S/PDIF is a good resource, tho I’ve seen BNCs used with S/PDIF more often than AES3.

With the DS whether you have RCA or BNC doesn’t really matter, use a converter if you have the wrong one. With some other DACs it might matter more: a BNC can be 75 Ohms like the coax, but it’s not technically possible to build a 75 Ohm RCA connector so there will be a small impedance discontinuity at the ends of the coax: often this is so close to the transmitter and receivers on the boards that I don’t think it usually matters a lot, but it can.

AES3 via XLRs is used in most professional equipment and is much more common than either AES3 or S/PDIF with BNC’s.

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I understand @tedsmith answer, but I’m not sure I understand the question.

You are contemplating buying more digital sources, and you want to connect those sources to your DAC by a method you’re not currently using, right? So, you need a source with AES/EBU output? I’m not clear how BNC has entered your thinking.

The question came up because it looks like I’m buying a used Lampi that will be upgraded to the current model, including adding a couple of ports for my needs. There is place for another set if I want and thinking ahead to potential needs led to my question. LampiNA had thrown out AES/EBU as an idea, but I’ve been reading lately of people using BNC instead of RCA connectors for coaxial, so I added that. That’s all. Just picking more knowledgeable minds. Thanks,

That sounds like a good idea. Go with that.

Get the AES/EBU input. As Ted said you can you an adaptor on the RCA coax input to get BNC connectivity.