One thing i didn't try, setting the default audio input with System Preferences to a 2-channel input. If so, I get:
etla:/Volumes/Namring/Documents/ChucK$ chuck --probe [chuck]: found 10 device(s) ... [chuck]: ------( chuck -- dac0 )--------------- [chuck]: device name = "Apple Inc.: Built-in Line Input" [chuck]: probe [success] ... [chuck]: # output channels = 0 [chuck]: # input channels = 2 [chuck]: # duplex Channels = 0 [chuck]: default output = NO [chuck]: default input = YES [chuck]: natively supported data formats: [chuck]: 32-bit float [chuck]: supported sample rates: [chuck]: 44100 Hz [chuck]: 48000 Hz [chuck]: 88200 Hz [chuck]: 96000 Hz
[SNIP]
[chuck]: ------( chuck -- dac2 )--------------- [chuck]: device name = "Apple Inc.: Built-in Output" [chuck]: probe [success] ... [chuck]: # output channels = 2 [chuck]: # input channels = 0 [chuck]: # duplex Channels = 0 [chuck]: default output = YES [chuck]: default input = NO [chuck]: natively supported data formats: [chuck]: 32-bit float [chuck]: supported sample rates: [chuck]: 44100 Hz [chuck]: 48000 Hz [chuck]: 88200 Hz [chuck]: 96000 Hz
[SNIP]
etla:/Volumes/Namring/Documents/ChucK$ chuck foo.ck etla:/Volumes/Namring/Documents/ChucK$
Works fine w/o any special arguments! Is ChucK cranky about non-default audio devices, then? Plus it seems that ChucK doesn't like asymmetrical (eg 1 in - 2 out) setups, perhaps because it can't set up duplex operation? Best, Charles