No, I don’t think so. The loopback test tells you what your total latency is. Of your AD/DA converter plus your soundcard buffer. I see no reason to adjust for that unless you use multiple converters with different latencies. Then it makes sense, for example if you use them together in a live environement.
But you can only delay the “faster converters” if you want to line up for monitoring trough your daw with the same latency for all converters. It’s impossible to speed up the slower ones on a live input.
An example; 64 samples buffer and 2x 64 samples (AD-DA) converter delay, so 192 in total will give you a roundtrip latency of 4,4 msec@44100khz. This is approximately 1,30 meter distance in real life…And phase can be only an issue if there is crosstalk or coherence between the sources.
So using the faster converters for mic inputs, and the slower ones for line inputs could be a solution too. Bas mic and d.i.(=coherence) is an example of something I would not put trough different converters…
Also for this reason:
Converters translate analog in to digital and vica versa. But they all do it different. So if you record the same source through two different converters, it will almost always be impossible to null the results completely (= low coherence).