Owners of Roland FA-06 or FA-08 can possibly help me with this.
 
I am seriously studying and considering the Roland FA-06 or FA-08 for purchase sometime in future to work in conjunction with Sonar as they have DAW integration with Sonar.
Being a studio music producer and not a live performer, one of the important aspects for me is the audio interface that is part of the FA-06/08. 
I already have my Roland Octacapture all hooked up. Now suppose I need to record audio directly from FA-06/08 into Sonar, an obvious way would be to connect audio cables from the FA-06/08 audio outs into inputs of the Octacapture.
 
But what if I want to directly use the interface of FA-06/08 (connected to my laptop through USB) ? That is, say, Sonar will detect the 2-in of FA-06/08 as stereo input in an audio track. I know I can do this. All I want to know is whether I can do this simultaneously with being able to use the Octacapture inputs as well for other inputs like say mics, other acoustic instruments, guitar, etc.
 
If say, on choosing the FA-06 interface, the Octacapture would have to get deactivated, then that would be a huge disappointment, for me rendering the use of the FA-06 interface as useless.
The reason I wish to go this way is because the audio recording from FA-06 directly into Sonar through its own interface (connected by USB) is most likely to be of better quality than recording the audio through audio cables routed to inputs of Octacapture. This avoids additional audio routing. 
 
A related question would be : Does FA-06 audio interface work with ASIO as the driver ? As I use ASIO for the Octacapture.
 
Hope my queries are clear. Thanks in advance.
 

Hi. Windows allows for only one ASIO device at a time.
You will have to use MME (I believe) to be able to use both.
All the best.
Edit: I might have misunderstood your question..

The ASIO spec allows the host to use one DRIVER and a time. How many devices are managed by the driver is the question. I see nothing in the FA-06 or Octa-Capture documentation that suggests these two devices may share the same driver or otherwise link together. That said,  I will have to defer to Roland or someone with both devices for the definitive answer.

The FA-06 ist basically the same as the Roland Integra 7. I cannot record from the Roland Octacapture and the Integra 7 at the same time with ASIO.
You can use WDM as driver mode. Than you can record from both at the same time.

I have an FA 06.  I can either use it as the interface to record FA via USB, OR I can have another ASIO interface enabled.  It's basically like every other cool piece of gear I have that has a USB interface built in. 
 
Believe it or not, the easiest way (for me) is to take the SD card out of the FA and put a guide track on it from my PC.  SD card back in the FA and assign the guide track as a sample.  Trigger the sample via the FA sequencer and play/record whatever accompaniments I want in the FA via MIDI.  Bounce the tracks to audio in the FA, then move the SD card back to the PC to pull them into a DAW project.
 
It would be easy enough to run the audio from the FA to a proper interface, but I use the main audio outs on the FA directly to my matrix for direct play/practice.
 
It is also possible to use the FA sounds by using it as an external sound module.
 
This is a limitation of Windows and ASIO, not necessarily anything wrong with the FA design.
 
Despite all of this ... I love my FA

FYI Zarg,, no one should resort to MME mode.  Always use ASIO and when two devices are running you can use WDM mode or possibly now WASAPI exclusive. 
 
WDM is what I use when recording a band live with 2 interfaces.  
I would not recommend staying in that mode for overdubs. 
It's pretty standard to use WDM mode to record a live band and then ASIO back in the studio where you will only need a few channels and one interface. 

 
Thanks so much everyone for your inputs. Does help a lot.
 
Only thing is, does WDM perform as good as ASIO ?
Can the same low latency be expected in WDM to the level that is usually observed with ASIO ?
Will all older projects open the same if set to WDM without any problems ?
 

You use ASIO if you desire top performance. All other modes not only suffer increased latency issues but cannot adjust timing offset so will not perform well for overdubbing. You use WDM or WASAPI for recording a live band, then switch back to ASIO for editing and overdubs. You'll see below results from a looppback test which shows where an overdubbed track will land on the timeline. This shot I was using asio4all because this is a realtech card. I would not be using that when I have a proper interface. But the results are the same for me with any interface. Only ASIO hits the timeline correctly which results in overdubs being in sync. All other modes are late. Wasapi Exclusive and WDM mode seem about the same, MME mode is obviously terrible. 

It's too bad neither has ADAT capability, you would be all set otherwise. Best bet as others have said is to use WDM, but make sure the clocks are in sync.
 

 
Thanks Johnny and Matt.
I don't know how much all this will be relevant to help me decide whether purchasing the FA-06 will be a good option for me or not.
But it sure helps to understand the differences between the various drivers.
 
Too bad one can't use ASIO for multiple interfaces. Its sort of a deterrent for me personally as my productions will involve a lot more of softsynths than live session recordings. So having to settle for WDM instead of ASIO for simultaneous use of the Octacapture and FA-06 audio interface may or may not prove to be a risk worth taking.
 
Guess I have to study and practically test this deeper in some way. 
 
Thanks once again.