I just got an Access Virus T12 Desktop module and have been playing with it for the first time.
The sounds are really amazing and the VST integration is great.
There doesn't seem to be a way to bounce the audio to a track if you're using the USB I/O with the Access plugin. Attempting to do so causes all kinds of havoc and creates a major dropout (audio engine reset). My ****e may be getting a bit complicated... :)
I have a mixer that I use for external synths and inputs, my Roland Fantom and my UAD 6176 goes through that and I routed the Virus through it as well. That works fine, you just have to remember to change the routing in the plug-in.
I'm not using the Virus as a sound card, I have a MOTU 2408 MkIII that works just fine for that.
It looks like you can have only one instance of the plugin if you have one Virus connected, but you get 16 MIDI channels of Virus so NBD.
My setup:
A&H 14:4:2 (direct outs) -> MOTU -> Sonar
ADAT 8ch preamp -> MOTU -> Sonar
Sonar -> MOTU -> Eventide Eclipse (SPDIF) -> MOTU -> Sonar (Fx Loop)
Monitor: Sonar -> MOTU -> A&H 14:4:2 (audio out, stereo channel)
This setup gives me 16 channels of analog input and one external effects loop (Eclipse) as well as a stereo monitor.
My solution:
Use an external mixer with direct outs to your audio interface, that way you can bounce the output to an audio track.
Connect the Virus analog output to the mixer or spend a lot of time tweaking the drivers and figuring out the latency for your final bounce. You'll have to patch it for every MIDI channel, they default to USB.
Use the Access VST for midi and patching, but leave the audio to your analog I/O. Personally I think it sounds a bit better going through the A&H preamp, but that's just me.
Make sure when you instantiate the Virus plug-in to create audio outs for the first synth, not an instrument track. That way you can route multiple MIDI tracks into the Virus (you get 16). Selecting the individual MIDI tracks will route your keyboard controller to the associated patch.
If my logic is confirmed, I should be able to use the Virus as a vocoder using:
Sonar (audio track) -> Virus (USB) -> A&H -> MOTU -> Sonar, but I haven't tried that yet.
Here is a picture:

I know I'm probably doing something wrong, but this seems to work ok for me.
Cheers!
 
 
 

Glad you like the virus, I love my snow :)

I recent froze rather than bounced to audio, this wouldn't work until I selected real time rather than fast freeze.

TomHelvey, have you figured out how to route audio through the USB to the Virus for FX processing or the Atomizer function? I cannot for the life of me see any sidechain inputs that are available to the Virus TI. And yes, I am in "3 out +1 in" USB mode. Can you or someone please post Sonar-specific methodology to sidechain audio (or direct output a track) into the Virus via USB?
 

TomHelvey
Make sure when you instantiate the Virus plug-in to create audio outs for the first synth, not an instrument track. That way you can route multiple MIDI tracks into the Virus (you get 16). Selecting the individual MIDI tracks will route your keyboard controller to the associated patch.

This works, but the real benefit of using USB instead of the analog outs is that you now have three, separate USB-stereo audio streams. Combine that with the up-to-16 part multitimbrality of the Virus TI2 (with about 100 voices of power) and the combination is insane! So you can route your bass patch to USB1-2; route your 3 pad patches to USB3-4, and route your 10 FX/transition patches to USB5-6...with each of the audio channels having their own set of in-box FX plugins. It is just want I wanted in a synth. The older Viruses A, B, or C didn't do separate analog outputs, which was a little dumb. The Q does, but that thing is and will remain in a league of its own.

Any issues related to bouncing a Virus Ti track in Sonar is something in your system or setup, as I have been using the Virus Ti with Sonar X1, X2 and X3 quite successfully.
 
In particular, given this is a real synth and not a soft synth, if you are using Virus Control VST and wish to freeze the track you must deselect fast bounce in the Freeze Options.
 
If you have done this, then it is possible that you have USB port issues. The Ti uses USB1.1 in isochronous mode and so must NOT share a USB hub with any other device as data corruption is very likely to occur.
Note that USB ports on a PC mainboard are typically in pairs, with 2 per hub. If the Virus is in one of these ports the other must not be used.