I've had the Clarinet since the beginning of this year (in fact, it was my last purchase of 2024) and since then I’ve spent a small fortune exploring connectivity solutions, so here's what works best for me.
1. USB OTG coax/optical converter sold by Dethonray
Probably the most versatile solution for anyone who has compatibility issues getting their source to work with Clarinet.
It's kind of similar to the SMSL P100, the crucial difference being that Dethonray's converter comes with cables that have been tested to work with the Clarinet.
So I've been able to explore all 3 Clarinet inputs and my preference is optical > coaxial > USB.
Optical is airier and more dimensional, smoother and with more extended treble. Coax has a slightly thicker midrange and a bit less air up top. Both to my ears are a step up from USB, which is why the converter is well worth exploring IMO.
But if you prefer to have a single cable rather than a converter dangling between your source and Clarinet, here is my next option.
2. USB type C to RCA coax cable + stock RCA to 3.5 adapter
For some of us, the struggle lies in finding a 3.5mm plug with the correct pinout to work with the Clarinet's coax in.
So I got round this with a type C to RCA coaxial cable, and then the stock RCA-3.5mm adapter that came with the Clarinet, to practically guarantee compatibility on the Clarinet side.
FWIW this is the one I bought:
https://www.aliexpress.com/item/4000589035319.html
If I had to do this all over again, I'd try a type C to optical cable as well. But since this would involve another $40 or so and I'm already happy with my options, it isn't likely to happen any time soon.
Not sure if you found a solution since it's been a while. I own an N7 as well, and can confirm that the above options work with it.
Don't bother with Cayin's type C to 3.5mm coaxial cable. It sort of works, but you have to pull the 3.5mm plug out from the socket slightly.
Gapless? Isn’t that a job for the DAP or source rather than the Clarinet, or what am I missing here?