Recording and MIDI Latencies in LogicPro

Good afternoon,

I've been spending some time remeasuring and testing key latencies within my system. Testing using Logic Pro on a well-spec'd imac from late 2019, lots of RAM, 64 buffer, 44.1k. Metric Halo ULN8 3D interface. Kawai MP11SE sending MIDI over USB directly into the imac for soft-synth control (no external MIDI hardware).

Do I have this test process right?:

Test 1: Starting from a blank project, I ran a loopback test and I/O ping test and measured a consistent recording delay offset of 51 samples. After entering that in Logic, I confirmed that audio waveforms align perfectly on loopback. Great, easy enough. (Sidebar: If I measure this delay right at the speaker, or in a headphone, another 20-30 samples are introduced. I don't know if folks adjust for that - transducer delay?? Maybe I goofed somehow, not sure - held mic right at the speaker cone).

Test 2: After tightening up recording delay, I played my Kawai controller with a drumstick, recording the tick of the drumstick as audio and comparing that to the onset of the matching MIDI event. At 120 BPM, I was off ~72 ticks, which is ~37 msecs. That seemed waaaay too high for a standard MIDI latency. I've never noticed latency that bad driving soft synths, e.g Garritan CFX. So.......

Test 3: .....I recorded audio out of the Kawai and compared that with the matching MIDI event. This produced an average difference of 4 ticks, so ~2msecs, which sounds more sane. I suppose this test excludes any latency caused by the keyboard generating its own audio, but that's never detectable. This in mind, I went back and redid Test 2 by just recording the 'thump' of the keyboard key bottoming out, which came closer to 4 ticks or 2 msec. So, presumably Test 2 suffered from a mechanical issue - a delay between drumstick hitting key and full depression/MIDI note triggering. (Unless Test3 is itself invalid? Seems ok....)

So, perhaps things end up 3 msec tighter after making these adjustments. Small, but I understand these delays can accumulate with overdubs (especially if you always focus on the most recent overdub when adding the next one).

Having done all this:

* What's the best way in Logic to correct for MIDI latency? There's a overall MIDI preference setting that I could set to -2 msec, but Logic also provides track/region-specific delays in the track inspector. I also have a Roland TD9 drumset that I'll subject to Test3; if delay values vary by MIDI device, probably better to use track-specific delay adjustments in a template? (and/or your ears, of course)

I've not tried other MIDI cabling alternatives, like a MIDI cable into the ULN8, which in turn transmits over USB. It's USB delivery in the end either way, but not sure if the ULN8 would provide a better USB path?

Appreciate any guidance on this one!