The limitation is the ASIO. 2 ASIO device can not be used simultaneously regardless of whether they are USB or Firewire.  As indicated above you could try it in WDM mode.  I was assuming that you just wanted to temporarily sub in the FA 101 to record your vocals and then you would return back to your original device.

Thanks Lorney,
I'll try that on Thursday.

What I'm trying to do is get set up so I can have all of my tube pre-amps (8 channels) recording at the same time.

I want to use the Alesis board for monitoring in control room plus be able to send separate monitor mixes out.

We're an old school Swingabilly band. When I start our record I want to be able to record drums & upright bass live off the floor to get that "live" feel. Hence the 8 pre-amp channels.