Why do I get high latency (300 ms) on a fast Mac, Firewire preamp, 16-sample buffer?

Question

Hardware: decent studio mic into Link.Firewire 4x6 (2518) preamp into early-2011 MacBook Pro (core i5), 8GB RAM.
Software: Audition CS5.5, no other apps running, Core Audio driver selected (which is the only option). Only one mono track armed for recording and monitoring, with no f/x turned on, routed directly to master output.
Symptoms: Regardless of the latency settings I select (16 samples up to 1024 samples), and regardless of the sample rate (44.1kHz to 96kHz), I still hear about a 1/3 sec delay when monitoring the input signal. Also same problem whether I route the audio output through the internal Macbook audio or back to the Link.Firewire monitor/headphone line.
Relevant history: I was able to do live multitrack recordings (overdubbing) with zero audible latency with the same Link.Firewire preamp on a wimpy old Pentium 4 3Ghz in Windows XP with Audition 1.5.
Why does this hugely faster Macbook Pro with Audition 5.5 have such awful perceived latency?
Thanks for any advice. I am already familiar with the latency-related literature such as the http://forums.adobe.com/message/3732874#3732874 and the Link.Firewire owner's manual. At this point I'm wondering if Audition 5.5 is the problem.

Answer 1

alan-ng.net wrote:
That sounds like a useful insight - but what do you mean by "So if in multitrack, the monitor option is set to Audition Mix, then you are likely to experience latency. If this is the case, then switch this to External ..."?
I don't see any menu options like this either in Preferences > Multitrack or in the Multitrack main menu.
Sorry, I keep forgetting that this is CS5.5, and that this aspect of it isn't the same as previous versions, so you can't control it like that...
It sounds like you might be talking about one of the configurations I already described above as tested and not any better: when Audition's Master  output is routed back to the LINK.firewire preamp's monitor output channel (as opposed to routing it to the Macbook's internal audio hardware).
The problem is that any monitoring output from Audition's Master output will suffer from through-path latency - as already mentioned. The monitoring control is now on the mixer - directly above the fader. You will find a button marked 'I', and this switches on and off the input monitoring on a per-channel basis. The important thing to note is that when you record-enable a track, the default setting of the input monitoring is OFF - and that's the way you should keep it! If you switch it on, then this is when you'll get all the latency I described, because the input will then be fed to Audition's Master output - and that's what you don't want.
So what you have to do then is to enable direct monitoring in your sound device, and this is where I think you will run into problems. I looked at the manual for your Link device, and I can't find any mention of an app to let you control any internal monitoring you'd need. Without this, you're stuffed unless you use an external mixer for monitoring, and just use the Link as a plain in/out interface - which is what, on the face of it, it seems to be. You'd probably be way better off with something like a MOTU 8pre, because this comes with a nice little software app that lets you control all of the internal monitoring paths very easily.