Optical or Coaxial input on NDX 2?

I am just about to take the plunge to add an NDX 2 to my system to complement my SN3. I will also use the NDX 2 as a DAC replacing my Roksan K3 DAC. I have the choice of running my CD player (Roksan K3) into the NDX 2 using the 75 ohm coaxial input or the optical input. For best sound quality which input is preferable (assuming I use an equally priced cable for either) ? Some sites seem to suggest coaxial has a wider band width so is preferable, but interested in hearing from the community. Many thanks for your views.

There’s a limit to the resolution optical will transmit, it is lower than co axial, but that won’t be an issue as CD is only 16 bit.

I prefer optical into ndac. I bought my favourite optical cable from a car boot for a fiver. No name, made in china, but glass not plastic.

I suspect the source has an influence on performance of any cable, in given system.

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Better galvanic isolation using an optical cable. Having said that I think Naim deigns incorporate internal optocouplers for isolation in their streamers anyway.

I can’t hear the difference between optical and BNC but that could be just my ears. I wouldn’t get too precious about the signal quality in the cable as the NDX2 accurately re-clocks the input signal and removes the jitter.

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@bitsrbits Is correct, there can be better galvanic isolation on optical, (though with some interconnects with metal parts and shields, that is by no means guaranteed).

Ultimately this is going to really depend on the quality of the outputs on the source. While Toslink Audio standard has a throughput limit that doesn’t allow some of the higher bitrate HD audio out there (it still allows for most), it is still a good mechanism. Though with optical you have additional transducers in the chain converting electrical pulses to and from light. Those themselves are not entirely benign.

On a high quality source with very little noise carried piggyback on a coax, coax should perform better. Remember the noise doesn’t affect the data but does enter the receiving end and potentially get picked up by the more sensitive analogue stages. On lower quality sources, optical may give better results.

A lot of people have tested this over the years and there was never a definitive answer. If this connection is for a quality source, it may be worth listening with two leads of similar quality and judging for yourself. If this is just for casual listening, you may want to just want to opt for whichever suits the price level of the source. With the Roksan, I’d guess that would be coaxial.

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Many thanks for the opinions. That’s a good point on the bandwidth - the cd signal is the limit rather than the optical cable. So I will just need to try both and see. I always learn something new by asking on this forum