For those that are thinking about connecting their N30LE as a USB DAC/amp to one of the new iPhone 15 series, I got mine this morning and gave it a try (15 Pro Max, in case it makes any difference):
The short version is that, with some USB-C cable-dependency - which only seems to affect iPhone and iPad, it works fine.
ALL of the below cables, when used with an M2 MacBook Air, M2 MacBook Pro, M2 Mac Studio or M1 Mac Studio will put the N30LE into USB DAC mode, and behave as expected.
The story is different with iPhone 15 Pro Max and M2 iPad Pro 11":
- Cayin Supplied USB-C Cable: Yes
- Apple Thunderbolt Cable: Yes
- Apple USB-C Charging Cable (2M): Yes
- Apple Braided USB-C Cable (1M) (as inc. w/ iPhone, AirPods Pro 2, etc.): No
- L&P W4 USB-C Cable: No
Will try other cables as I get a chance.
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For reference, ALL of those cables work with the iPhone 15 Pro Max and M2 iPad Pro and the L&P W4. Which makes me think the N30LE or iPhone is looking for some pin/setting that the W4 doesn't care about.