I'm using the digital output from our iMac to directly feed an Ultra DAC, T8 and FET Valve 550exr. I've ripped most of our CDs into iTunes via the AIFF format, which is uncompressed and lossless. I can hear no difference from the original CDs. Like Brett, I can hear a difference with iTunes Plus, though it's not bad. And it's fun to make playlists and shuffle!
Craig
If nothing else, it's a great way to keep track of and find music. Sorting through hundreds of CDs to find the one you want is no small problem. Until I set this up (enabled by the Insight+ DAC) I didn't fully appreciate the genius of iTunes. It's not the store, it's not the compression schemes, it's not the iPod loading, it's the ability to sort and find the music.
Brett
p.s. idle question, and maybe I am missing something obvious, but how are you getting a digital audio directly from the iMac? Near as I can tell, my pretty new iMac doesn't have anything aside from an analog audio output. Some gadget hooked to USB? I am using AirTunes.
The analog audio output is also an optical digital audio output. The port automatically selects digital or analog based upon the cable. When you plug in the optical digital cable, you can verify that the output is optical in the sound preference panel. Just slip a 3.5 mm optical digital adapter ($2.99) on a toslink cable and the headphone/speaker port transmits optical digital (red light). I just needed the toslink to coax adapter in order to connect a digital coax cable to the DAC. Last week, I went to the Apple Store (only because I was in the mall, a rarity in itself), and I asked a genius if they had a 3.5mm toslink adapter, and the genius asked me what was toslink. Then, when I explained how I intended to use my iMac as a music source, he questioned my reasons for wanting to convert digital to analog. I tried to tell him that CD players and computers have built-in digital to analog converters and even iPods have built-in digital to analog converters. I asked him how he thought the red light (aka the digital output) was converted to sound, and asked him if they sold digital headphones, and he gave me the smirk that says, "You, sir, are an idiot" (not an ahole; just an idiot). He could be correct, but I think that Apple merely refers to them as geniuses. Any genius testing is probably not very objective.
BTW, the Airport Express also has a 3.5mm audio port for analog or digital output. If a non-optical cable is used, I suspect that the signal is analog because the jack/port automatically selects whether the output will be digital or analog and the signal will have already gone through the computers built-in DAC, defeating the potential of the AVA DAC, but maybe not. Also, if you used an analog 3.5mm jack, I don't know if you would use a mono or stereo analog 3.5mm jack that terminates as an RCA plug and how a mono or stereo jack would effect the input to the DAC. I don't know enough about the iMac's or AirPort's operation to speak competently.
I ran cable rather than using AirTunes because my computer is near the DAC, the cable and converter (about $50.00) was less expensive, I hardwire everything, if possible, and I don't know anything about AirTunes.
