Confused about adapter for RCA to BNC

I have used any number of 75ohm, off-the-shelf, BNC-RCA and RC-BNC adapters (often marketed for video use) for S/PDIF connections without any problems.  Never paid more than $2 for any of them.  What have got to lose?

@stuartk - I have the same DAC as you and used a BNC cable (Oyaide 510 ) with adaptors without any problems.  Later, I needed a longer cable and purchased another of the same cable except the longer cable had rca connectors.  I compared the cable with adaptors vs. the longer cable without adaptors and I heard no difference between the two.  Even compared to AES/EBU, I did not hear any reliably consistent differences.  USB may be just a tiny bit better sounding, IMO, but the perceived difference may also be personal preference.  
You found and linked a fancy-schmancy Cardas adaptor.  Just make sure you get the female bnc to male rca version.  In contrast, I used the type of adaptor kr4 was referring to and exactly what was linked by @knownothing for the comparison I described above, and it worked and sounded just fine for under $2, which is what  it should cost to resolve your issue. 

If you wish to lighten your bank account a little more, here's another solution.

@stuartk   It usually is always better to follow the KISS principal.  (Keep it simple...)

Adapters, while they work, sooner or later can cause problems. The extra connections on the signal path, potentially cheap construction, and potential impedance mismatches with adapters...

So, +1 to carlsbad2 and audphile1, get either a good coax/spidif cable (RCA's) or and AES/EBU.

my 2 cents...

@stuartk Like some others here, for years I’ve used a much cheaper adaptor to the Cardas adaptor you already found with no problems or sonic compromise. Let your brain be your guide, not necessarily what you read. BTW, love your Craftman style home and listening area.