Using Reaper to do this might be a good option. Each track can be set up to output to a different channel, however, you're going to run into a serious problem with the Delta 44 in this regard.
Outputs 1/2 are also the Monitor outputs. I do believe that in the control panel, you can leave the output of channels 1/2 to only be channels 1/2, and let reaper load the Wav files, and loop them, sending each to a different room without problems.
Since you're managing playback and not recording, I'm fairly certain you wont run into any of the weird static recording issues with this setup. The AMD x3 setup should have plenty of power on tap, and shouldn't give you any problems with this.
Setting up Reaper for this would be a fairly easy task, even for someone who's never used it before. The licensing cost is also on the money, being so cheap and giving a lot of flexibility. Given the trial period that Reaper has, I would strongly suggest giving this a try.
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