Thanks PRC. I'm sure that's it but I'm still missing something. So I'm going to ramble on here, subjecting the list to my failures. - I did have Blackhole installed; I uninstalled it and rebooted but still no dice. Haven't used Airplay recently but I do remember its annoying propensity to show up as default. Here's my probe: hamilr4-mbp15:Desktop hamilr4$ chuck --probe [chuck]: found 2 device(s) ... [chuck]: ------( audio device: 1 )--------------- [chuck]: device name = "Apple Inc.: MacBook Pro Microphone" [chuck]: probe [success] ... [chuck]: # output channels = 0 [chuck]: # input channels = 1 [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 [chuck]: [chuck]: ------( audio device: 2 )--------------- [chuck]: device name = "Apple Inc.: MacBook Pro Speakers" [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 So if I run the pitch-track.ck example (timeless) and print out target_freq near the end of the main while loop, I'll see fluctuating output as expected when run in mini-audicle. Nothing in terminal. I'm trying: chuck --adc0 --in1 pitch-track.ck or chuck --adc:0 --in:1 --srate:48000 pitch-track.ck or to be more explicit... chuck --adc:0 --in:1 --dac:0 --out:2 --srate:48000 pitch-track.ck (both should work right? i.e. colon or no-colon) and just get a wall of: 0.000000 :(float) 0.000000 :(float) 0.000000 :(float) 0.000000 :(float) from Terminal, vs. the expected: 46.875000 :(float) 93.750000 :(float) 46.875000 :(float) 93.750000 :(float) 93.750000 :(float) plus sweet sine-waves in MiniAudicle. Interestingly enough, MiniAudicle only shows my output devices under Device Browser > Audio Interfaces (i.e. MacBook Pro Speakers here). Can't remember if it always only showed output and not input?