Playing synchronous sounds on two different speakers out of a set of 8 randomly

I just downloaded p_wavplaya to play multichannel sounds. I also have PsychToolBox's PsychPortAudio.

I plan to use it to play sounds on 8 speakers. I have a slight problem with implementing it though. I need to simultaneously play 2 sounds, one always from speaker number 3 and one from the other 7.

    pa_wavplay([stdSound cmpSound], fs, [deviceidstd deviceid], 'asio')

deviceidstd is my device ID 2, which is where the 3rd speaker sits and deviceid takes on a variable depending on which speaker my randomizer selects for that trial.

I have not yet tested it out on the 8-channel sound card, but I was wondering if this sort of a syntax works? stdSound and cmpSound are both Nx2 matrices. stdSound should play from deviceidstd and cmpSound should play from deviceid. Because I want them to be synchronous, I will not code them one after the other.

Will this work? If not, I'd be grateful if you have any other suggestions.

Thanks