Stereo to multichannel USB interface

Question

Hello, I'm having a bit of a problem with my sound.
I bought a Hercules Gamesurround MUSE Pocket LT, a USb interface for 5.1 audio.
I've got it working with 5.1 games and movies but I'd like to output iTunes to all of the channels (so not real 5.1, but just fake it) as well as all other applications that output sound.
At this point I wouldn't even care if I lost the 5.1 surround, I only want to have the music coming out of all of the six speakers. I've used splitters in the past but for now that's a no go. It's a long story.
SO are there any drivers that output stereo to 5.1/multichannel ?
I've tried "USB Audio ASIO driver" but it only puts a beep every few seconds on the output and still uses only 2 speakers.

Answer 1

YAY!!!!
together with AULab from Apple, soundflower can set up stereo->surround audio.
http://www.insanelymac.com/forum/index.php?showtopic=148492
Quote here for future reference:
Parastie wrote on the insanelymac forums:
It's taken me quite some time to figure this out, and considering how easy it was I should have gotten this done a long time ago. For a little bit of history, I purchased a X-Fi Surround 5.1 for my Macbook Pro. Anyone who has this sound card knows that it has wonderful audio quality, or at least in Windows. In Mac, it has no ability to upscale stereo sound to 5.1, which is something I really enjoy. I have this device connected analog out to 5.1 speakers, and here's how I got it all to work! I'm using OSX 10.4, and the instructions should be similar for 10.5.
1.
Download SoundFlower
http://code.google.com/p/soundflower/
2.
Make sure you have AULabs installed. It's part of the Dev Pack, so check
Developer/Applications/Audio for the AULabs
3.
Now we need to make sure that OSX knows that you're dealing with surround sound stuff. Once you have everything installed, go into the MIDI Configuration panel, listed under Utilities.
3a: Under the 'Properties' category, you need to select your SB X-Fi Surround 5.1. Click on Speaker Configuration and choose Multichannel, then select 5.1 Surround. Make sure you click apply!
3b: Again under 'Properties' choose the Soundflower (16ch). Click on Speaker configuration and choose Multichannel, then select 5.1 Surround. Make sure you click apply!
4.
This is where things get interesting! Launch AULabs. For Audio Device, choose Soundflower (16ch). You can experiment here, but I found it easier to add filters by manipulating each channel seperatly.
4a: So under Outputs, look for Output Channels and choose 'mono'. Now you'll need to add 6 channels. To prevent crossing signals, you need to make the channels 11-16, instead of 1-6. Now click on Inputs and add channels 1 and 2. Click Okay.
4b: Now, you should have 2 channels under Audio Device and 6 under Master Out. Under Audio Device, look down where Volume is listed. You should see numbers 1-6 listed for each channel. These numbers correspond with the Outputs. For Audio 1 (which is the left channel), you want to choose 1,3,4, and 5. For Audio 2 (which is the right channel), you want to choose 2,3,4, and 6.
4c: Remember, you don't want to close this window, but you can choose File and Save, to save this right now.
5.
Now we're going to configure Soundflower using Soundflowerbed. Under Applications, open the folder for Soundflower and launch Soundflowerbed.
5a: Soundflowerbed is an application that hangs out in the menu bar at the top right. Click on it and look at the Soundflower (16ch) and you want to choose your audio device. for me, I chose SB X-Fi Surround 5.1.
5b: Click on Soundflowerbed again open the drop down menu for the Soundflower (16ch). What we need to do is route sound to the proper places. Under channels 1 and 2, you want to choose 'none'. You might also want to change channels 1-6 to 'none', but that's up to you.
5c: Now you need to route channels 11-16 to the proper places. 11 goes to SB X-Fi Surround 5.1 [1], 12 goes to SB X-Fi Surround 5.1 [2], 13 to 3, etc.
6
Play something! You should have sound going to all 5.1 speakers! Experiment with some filters in AULabs. I'm using the AULowpass filter on channel 4, which is the subwoofer and i've been tinkering with Hipass filtering on the center channel to isolate voices.
Let me know what everyone thinks. There might be a way to use this application to build a true application, but I don't know how. the AULab must be running for these features to work. If you close it, the audio will stop. Enjoy!