Technically, most cab IRs only contain useful data below that length anyway. So you normally would have to make your own IRs to be custom length. Of course, some are '500ms' or '200ms' etc... but the actual file can be inspected in your DAW like any other .wav, and you'll find practically nothing useful.
Here is a randomly chosen IR (ownhammer h30)
Nothing to see past about 2500 samples.
If you are THIS serious about your IRs being 4096 samples in length
and actually own a NAM Player unit then, by all means import your custom IRs into it and enjoy the full amount of cpu cost, for very little returns or any meaningful difference in 'tone'.
Happy that it supports 4096, but it's really a trace detail - and absolutely bizarre to be going around in circles about it when there's no way it can be anything but 'what it says on the tin'.
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