OAS Playout Technical Resources: Installing 2 sound cards
These notes (I hope) will serve as useful information for anyone attempting to get 2 sound cards working on a Windows PC. They are based on my experience on installing OAS Playout (which runs with 2 sound cards) onto various machines. If you've found your way here through 'Google' or another search engine then its probably because like me you thought its all quite straightforward only to discover that in reality its a nightmare. These notes may help, if not feel free to drop me a mail - I might have something insightful to add.
What definately won't work
Generally speaking putting any two identical soundcards in a PC won't work. The classic case is your PCI SoundBlaster Live! - it's generally well known you can't put two of these in a machine & expect them to work. I say generally because I'm reliably informed that you can get two of the old ISA SoundBlaster Gold AWE64s working together (although I couldn't) so in some instances it's possible. However my personal belief is that you are setting yourself up for an uphill struggle by attempting this.
What will work
A very good bet is pairing up cards which operate on different physical buses in the PC - if you've got an older machine (& an older card) a PCI+ISA pair shouldn't give any problems - PCI+USB is another option. Even cards from the same manufacturer will be fine here. I've also had reasonable success with a PCI card + on-board sound equipped motherboards although these are probably on the PCI bus as well it's just they often use some obsquere chipset so you get lucky.
The grey area
Unfortunatly will the demise of the ISA bus & associated peripherals and for cost reasons the likelihood is it's a PCI + PCI pairing and this is where the problems arise. In my experience (mostly with Windows 2000) the symptoms are that the 2nd card either won't play any audio (try going through the Sound & Multimedia option in Control Panel & play some of the Windows sounds through both cards - the failing one will just refuse), applications crash when using it or the whole machine locks when using it.
There's the obvious things to try - get the latest drivers for the relevent cards etc etc. Outside the obvious, here's my list of things to try:
One of my initial annoyances with the whole 2 soundcard issue was even needing two at all when cards like the SBLive have multiple outputs, it's just you can't physically drive them independently. However following on from my investigative work into ASIO it seems that if you use the alternative drivers from the kX Project you can do just that using the kX DSP router. After I installed the driver, I ended up with 4 output devices, all labelled "kX Wave" with pairs of outputs (0/1, 4/5, 6/7 etc.) In the default configuration it doesn't seem to matter which one you use ie. it works pretty much like a normal Creative driver. However if you open up the kX DSP you can route the inputs (from the FXBux - here are the 16 [mono] inputs) to the outputs (marked 'epilog'). I disconnected pretty much everything else and just connected say Fx bux 4/5 to 'Rear Out L/R' and ended up with an independently controllable sound card. I'm sure there's loads of other clever stuff you can do if you read the manual...
This from Peter Gackowski: "any Soundblaster card works seamlessly with Yamaha sound cards built on YMF 724 chipset - tested on Windows NT4.0 SP 6 and W2K" - Thanks Peter.