I stayed up until 3 a.m. Friday night running between my computer and listening rooms. I was trying to push a high bit, expanded frequency WAV music file from my Mac Mini‘s iTunes to my Airport Express’s connected to my hi-fi set up. This experiment failed but I learned something that will make me pursue a new experiment that I always thought silly before.
The Airport Express’s can only pass a 16 bit, 44.1 khz audio signal through its digital optical output (and DTS streams, haven’t tried this one yet). The funny (frustrating) thing is iTunes has no problem playing back a 24/96 WAV song. When you send that same song to remote speakers with Airtunes it is down sampled to 16/44.1. I should have read Stereophile‘s review closer, this fact is clearly stated.
I tried to trick the Airport Express by taking iTunes out of the signal path. Instead I used Airfoil to redirect any of my system audio to the Airport Express. Playing the same high bit WAV file through Quicktime resulted in the same 16/44.1 at the Airtunes end.
The bit rate (depth?) was verified by the display of my Onkyo TX-DS989 AV Receiver. I’d try a new trick on the Mini (Audio Midi set to resample system audio, play song in iTunes and capture stream with Airfoil) only to run downstairs and have to look at another "PCM fs: 44.1" on the Onkyo’s green display. (All the Airtunes experiments were done with the AV receiver muted, so as not to disturb the sleeping wife and kid. The silence made the 44.1 readout more depressing each time.)
Saturday, I had the bright idea to hook up my Powerbook with its digital audio optical out to the Onkyo. Just as I described in Friday’s post the Powerbook passed "PCM fs: 96." It worked for both true 24/96 samples and re(up)sampling normal compressed iTunes music. The Onkyo still displayed 96 khz even when the Powerbook sent 88.2 khz, odd. So, if you can directly connect a digital audio output capable Mac to your processor then you should have no problem enjoying high bit rate fidelity.
With this new knowledge recording vinyl LPs onto the Powerbook at high bit rates should be possible. Could I capture the magic of vinyl with really high quality digital? Could I get rid of vinyl’s noisy annoyances through software? Can hi-fi and convenience finally meet and shake hands in my listening room? I hope to answer all these questions in the following week while comparing different shareware and professional recording software and their associated tips and tricks.