I have an HDX/HD IO rig that I also use for IO with Cubase 11 via CoreAudio.
Ultimate 2021.7. Mojave. Cubase 11.0.10.321
When playing with VI's, I was finding the latency I was experiencing regardless of buffer settings to be a bit high. So I thought I would do some tests. I used the RTL utility to test the IO directly and got some strange results - it said that the reading was very different from the latency reported by the interface - so I launched ProTools, turned off delay compensation and recorded out to in to see what I was getting. The result was 76 samples at 48k and half that (predictably) at 96k. So ~1.5ms on the former and less than a millisecond on the latter.
So I quit Protools and launched Cubase at 96k, 256 buffer size. Put some audio on a track and routed it out to in and recorded the results. Except at every sampling rate, I got absolutely no delay - which means that the system is compensating automatically (as the manual says it does, compensating for the reported latency of the interface). And I thought, okay, that's great, but I need to see what the actual passthrough is when using CoreAudio - since the Avid drivers are suspect here. (They are suspect because I can use my Grace m900 USB IO - a glorified headphone amp, though a very nice sounding one - and use smaller buffer sizes with VI's than if I'm using the Avid stuff. )
I turned off ASIO delay compensation and found that my RTL was 2108 samples (22ms). Empty session but for two audio tracks; no inserts anywhere or on Control Room; and 1254 (13ms) samples when I turned off Control Room. Cubase reports 8ms in and 8ms out, but that's a different number when added than 13ms. At 128 buffer at 96, the delay is 11ms.
Can anyone help me account for all this? Could Avid's CoreAudio drivers be that bad?
Please no "Avid sucks and that's why I blah blah" posts - I'm looking for science here. And it's funny how people who quit using Pro Tools sometimes find the time to post here anyway.
