Multiple input device recording/mixing help in Audition 5.5

Question

I'm presently evaluating Audition 5.5 and haven't been able to find any information pertaining to what others MUST do everyday.
I'd like to use Audition to record simultaneous tracks from different sources (microphones).  I'm using several USB sound card dongles (each with a single 3.5mm stereo microphone input and headphone/speaker output) as quick and convenient method of creating an array of microphone inputs.  Each dongle appears as a discrete audio device with a corresponding input and output.
Fine so far.
Where I'm struggling is in trying to map each microphone to discrete mixer channel.  I choose Edit->Preferences->Audio Channel Mapping, but it seems that only channels from any one particular sound device may be mapped to mixer channels at any time.  If I assign the microphone from sound card A to Track 1, I can't assing the microphone from sound card B to Track 2.  When I try, it alters the hardware device selection and negates any prior channels I've mapped that aren't part of the same device.  I hope I've explained the situation clearly.
I'd like to map the microphone from sound device (dongle) A to Track 1, the microphone from device B to Track 2, C to 3 and so forth.  But I cant' seem to figure out how to make Audition simultaneously recognize more than any one sound device at any particular time.
Is there a way to do what I'm trying to achieve?  Does Audition not support simultaneous mixing/recording from multiple hardware devices?  If not, do other products exist that DO support the configuration I'm trying to create which I can use as a front-end - to later mix-down in Audition?
I'd greatly appreciate any helpful insight, guidance, suggestions or recommendations.
Thanks!

Answer 1

remford wrote:
I'm not having any SYNC problems that I'm aware of...
Of course you're not - that's because the system prevents you having them by limiting the physical sources you can use!
Here is a brief explanation of the sync problem - I hope it makes sense:
When an input device digitises a signal, it has to provide a clock source for its A-D device. Normally this clock is locally derived, and the device outputs a digital stream at that rate. But if you have two devices (let's say that they were two external USB ones) both trying to be the input device, then their clocks won't be synchronised - inevitably. Audition, and all other software come to that, can only record at one rate, and if another device provides an input that isn't exactly at the same rate and phase as the one providing the master clock, then fairly soon, you get to a point where the data being inputted won't coincide with the main clock any more, and a bloody great click occurs. On older systems where you could use multiple devices, some allowed for the clock sources to be externally synchronised, and a lot of pro gear still does - it helps a lot when you are using digital mixers and external digital preamps if you can feed everything from a master clock, rather than daisy-chaining it.
When it comes to ASIO, Steinberg made the relatively easy decision not even to try to implement it for multiple devices. Instead, they suggest that you use a single device which is capable of supporting as many inputs as your PC can manage. As an example of how this works, my MOTU device that I mentioned above has eight analogue inputs, and also an 8-channel ADAT input. So, without too much trouble I can connect an external 8-channel digital preamp to it and have 16 inputs in total. It uses an optical connection for the ADAT, but to use it I either have to provide sync from the MOTU to the preamp, or use the preamp as the sync source for both itself and the MOTU, replacing the internal clock. With the only digital preamp I have it's this latter option that makes sense, as there isn't an easy way to get sync from the MOTU back to the preamp. (I should perhaps explain that the preamp has got a sync input, but the only sync output from the MOTU comes from its ADAT output, and that isn't easy to feed back in).
Yes, until you get used to it the concept of syncing devices takes a bit of getting used to - Steinberg's idea was to keep it as simple as possible, even though on the face of it, it's rather frustrating.