No, not really.
I can go way over 100 volume, even on balanced output, with other headphones (i.e. not IEMs) and not get any audible distortion from doing so. So I very much doubt that’s a factor.
I don’t have either of the IEMs you list to test with, but I can tell you that if I switch, say, the EE Odin to the single-ended output, then on the tracks you listed I can’t get anywhere near 100, let alone 111 on the volume setting.
If you do, and you’re not deaf yet, you very soon will be … or will at least just be a few seconds away from permanent hearing damage. Obviously that will be potentially different with other IEMs.
Yes, it affects all audio output.
But filter differences are very small, unless you know what you’re listening for, and even then you generally do have to listen specifically and in a focused manner. And, of course, the material you’re using has to have content that can expose the differences (telling a super-slow vs. super fast roll-off filter apart audibly requires material with significant higher frequency energy/content, where as telling linear vs. minimum phase filters apart is much easier … if still not obvious until you’ve had the ability to listen properly to both in controlled conditions).
Probably the best way to go. Sounds to me like your unit has issues with its output stage. Though I’d try a full factory reset before doing that, just in case.
And you only mention this via TIDAL. Is it happening with local lossless content too, i.e. off the internal storage or a microSD card?
The SP2000 can too … I can’t reproduce what you’re finding, so unless it’s some odd interaction with the IEMs you have (which I highly doubt), I suspect you have an issue with your unit.
Oh, I ran into all kinds of issues with the Cobalt. Run off iOS devices it would usually get disconnected (“This accessory is drawing too much power.”) before it would crash - but sometimes it’d manage to crash before iOS stomped it.
Very easy to reproduce, with headphones I would not have expected it to also. Never had that with the Red version.
The Odin with the Cobalt should be a laugh, as it’s half the impedance of the Nio …