Why the latency happens for recorded audio from a digital source
 

Hi there,
Maybe this more related to audio basics, and maybe this doesn't matter as we probably can't hear any difference, but I just want know some basics regarding digital audio how it works.

So I have 2 DAW running, I sync PT and DP via MTC. I play a drum hit sound in DP and have it output via loopback (or ADAT, etc..) and record into PT. Every time the exact position of such hit sound is slightly different.
I can understand there'll be a lantecy for me to hear this sound in PT, as there's roundtrip latency and because it's live record there's no delay compensation. But why the recorded position is also different every time? There's a one trip latency in this "roundtrip latency" ? Shouldn't PT automatically compensate for this delay and put the recorded audio at the correct position every time ?

Re: Why the latency happens for recorded audio from a digital source
 

MIDI time code is far from sample accurate. While your I/O delay is constant, there’s quite a bit of slop in the timing when syncing with MTC. If both DAWs are clocked to the same sample clock, there won’t be any timing drift, so the random difference you’re seeing has to do with how quickly the chasing DAW locks to the MTC.

Re: Why the latency happens for recorded audio from a digital source
 

Ok, so MTC caused the problem. BUT:

I tested: DAW Ahas a midi track sends out Midi data to DAW B instrument and record the audio back into DAW A audio track using: sound flower, physical ADAT, loopback2, all end up with different location very slightly. What is the reason for this? There's no MTC involved