davidmesiha wrote:I noticed that once I'm in rewire I'm not able to change the buffer setting for Notion, but I can do so for Logic! should I first launch notion and set up the buffer,then quit it, then start logic and restart notion?
Yes! 
It is easy to do and just takes a minute or so on a fast Mac . . .
davidmesiha wrote:. . . would you recommend higher or lower buffer settings to ensure best timing? obviously normally if I'm recording live, then lower buffer uses higher cpu but results in more accurate timing, how does this apply to the case of rewire?
Generally, I use Digital Performer 8 (MOTU) as my primary DAW application on the 2.8-GHz 8-core Mac Pro (early-2008) with 20GB of memory here in the sound isolation studio, and I use a MOTU 828mk3 Hybrid external digital audio interface, which among other things is the way I connect XLR microphones and analog guitars and synthesizers to the system and digitize them so that the Mac Pro and corresponding digital music production software can use the audio information, but I also use Logic Pro 9 (Apple), although mostly to help Logic Pro 9 folks get ReWire 2 working correctly, and I also use Reason 6.5 (Propellerhead Software), which I just upgraded to the new version (Reason 7), which is an interesting self-contained digital music production application and environment that can be expanded using the new Rack Extension technology and products, where it is useful to know that Propellerhead Software is the company that does ReWire 2 and that you can control and play Reason instruments and synthesizers via a "virtual MIDI cable" using music notation in NOTION 4 External MIDI staves, where the music notation for the Reason instruments and synthesizers in contained in some number of NOTION 4 External Staves and is sent via "virtual MIDI cables" to Reason, where Reason does the audio generation and can do this in a ReWire 2 session where either (a) Digital Performer 8 or Logic Pro 9 is the ReWIre 2 host controller and (b) NOTION 4 and Reason 6.5 or Reason 7 are ReWire 2 slaves, which is all the more mind-boggling in terms of technology because in this scenario the DAW application is controlling both NOTION 4 and Reason 6.5 or Reason 7, but simultaneously NOTION 4 is controlling and playing some of the instruments and synthesizers in Reason 6.5 or Reason 7 . . .
The rule I use regarding Logic Pro 9 is to set its buffers to the same size as the NOTION 4 buffers, which for ReWire 2 in 64-bit mode currently is "1024 Samples", which I changed recently after doing some experiments and observing that the Mac Pro can handle it, and the following screen capture shows how I have the Audio and ReWire 2 parameters set for Logic Pro 9 . . .
[
NOTE: It is important to have an Input Device and Output Device, even if there is no actual Input Device. If you do not specify an Input Device, then something does not work correctly, although at the moment I forget what, except that it is involved in being able to monitor stuff or something. Also note that you want to use standard CD quality, since this is what NOTION 4 outputs, so you want to uncheck the 24-bits option in Logic Pro 9, which causes it to do 16-bit audio and is what you want. The sample rate needs to be set in Logic Pro 9 to 44,100-Hz or 44.1-kHz. I set the "ReWire Behavior" to "Live Mode (Higher CPU Load)" based on the thinking (a) that the Mac Pro has dual quad processors (8-cores total)] and (b) that ReWire 2 is time-sensitive, hence giving it as much processing, buffer, and memory resources as possible should make it peppy. Whether this makes any actual sense is another matter, but it works nicely here in the sound isolation studio when I am using the MOTU 828mk3 Hybrid to offload some of the audio processing, which also helps . . . ]
Logic Pro 9 Preferences ~ Audio/ReWireRegarding latency, synchronization, and so forth, ReWire 2 handles the synchronization, hence everything is fine in that respect, and the strategy I use is to record the NOTION 4 and Reason 7 generated audio in the DAW application, which in this example is Logic Pro 9, in a separate ReWire 2 session, where only the NOTION 4 and Reason 7 generated audio is being recorded in the DAW application, where by doing it this way the latency does not matter . . .
When I decide to record real instruments and singing, I do this separately in Logic Pro 9, at which time all the virtual instruments have been recorded as "soundbites" and there are no latency issues other than perhaps the latency of any effects plug-ins that I might be using, which usually is not a problem, but if it is a problem, then I temporarily disable the effects plug-ins . . .
And the only actual latency problem that happens is when I use certain types of effects plug-ins on vocal tracks in real-time, which does not work, hence I usually do vocal tracks dry or use real external effects units . . .
I made a YouTube music video showing Logic Pro 9 controlling NOTION 4 and Reason 7 using the aforementioned Audio parameters and ReWire Behavior (
see above), and it is online now. There is no voice-over, but it should be self-explanatory. You can change the viewing resolution to HD (720p) and should be able to see the various parameter values, which is fabulous . . .
LP9 N4 R7 ReWire2 64 "Faster" (Techno Squirrels) ~ SurfWhammy Remix -- YouTube music videoFabulous! 
P. S. The best way to determine the parameter settings that work best with your computer, software, and so forth is to do some experiments. I was using "256 Samples" for the buffer sizes, but I did some experimenting and I think using "1024 Samples" works better for several reasons, so I am using the larger Audio Buffer Size now, really . . .
Really! 