[Darryl Ramm]

I suspect other users here (like me) are having problems following what you are doing and why you are doing it.

If I follow you (but please correct me) you are sending MIDI to Pro Tools (from a Cubase MIDI track?) and hosting a RTAS VI in Pro Tools HD? And then recording back the monitored audio into Cubase... I'm not following why? That is a messy setup. Pro Tools HD system is arguably a poor choice as a VIs host, why do you want to run RTAS VIs in it... and you've got Cubase why not host the VIs there?

If you are doing something different please explain.

And what latencies are you after , how many ms/or samples? What latencies are you getting now (actually measure it). I am not sure what you mean by 'groove' -- how small a latency do you expect/need? -- I want to make sure you have reasonable expectations. You cannot magically avoid the combination of I/O Buffer related latency in Pro Tools (one transit of the I/O buffer going to the TDM mixer in the case of a VI) and and any potential latencies from MIDI processing thats a very real time delay.