Streaming audiophile quality from iTunes - mac hardware limitations?

Question

I listen to a lot of classical music and have recently been experimenting with commercial 24 bit/96 kHz and 24 bit/192 kHz FLAC files converted and imported into iTunes using Max, as AIFF or Apple lossless files (there are some recent issues apparently related to Snow Leopard that make this a bit more clunky than it was, discussed in the Max forum)
The files are appropriately huge (9000+kbs for AIFF 96/192 files) which should keep all the bats and dogs in the neighbourhood happy if I had the appropriate gear for playing it. I have recently been looking at various hardware (Naim and Linnwood most recently) but their dedicated ways of playing back the music are very clunky if you are used to iTunes - i have no wish to change.
However It is possible to directly stream digital (at a max of 24/96 for Naim and 24/192 for Linnwood which looks good - with the very minor disadvantage of no display of track info on the units themselves.
But this raises several questions:
1) What are the hardware limits for digital out on modern macs (the computers, not iPhones or iPods) - can they really stream 24bit at 96 or 192 kbs? Or do they downscale, to 24/48 (i think) like the Squeezebox?
2) I believe that anything over 24/48 is not very practical over wireless (and I already know that Airport express in any case has a limit of CD quality 16 bit). Of the alternatives, eithernet is possible with some sound systems and presumably distance between computer and music system is not likely to be a problem. But - question 2 - are there practical limits on distance for wire and/or optical digital connections from computer digital out to sound system?
Cheers
Malcolm
Message was edited by: Malcolm MacGarvin

Answer 1

Malcolm MacGarvin wrote:
1) What are the hardware limits for digital out on modern macs (the computers, not iPhones or iPods) - can they really stream 24bit at 96 or 192 kbs? Or do they downscale, to 24/48 (i think) like the Squeezebox?
You don't mean kb/s - this is the bitrate, used with formats such as MP3 where the bitrate can be specified. You mean the sampling rate, which is specified in kHz. 192 kb/s is pretty mediocre quality for stereo. The bitrate for CD quality is 705.6 kb/s, for 96 kHz 24-bit is 2.3 Mb/s - these are dependent on the sampling rate and bit depth and are not further configurable, so are not usually quoted for uncompressed audio. (An actual CD has a higher bitrate because of the extra bits required for the strong error correction.)
CD quality is 44.1 kHz; 96kHz is the usual maximum. The maximum setting in Audio-MIDI Setup on my 2008 iMac is 96 kHz 24-bit. I'm not in a position to test how this works with iTunes.
But - question 2 - are there practical limits on distance for wire and/or optical digital connections from computer digital out to sound system?
I have an optical lead running 10 metres and a coax lead running around 9 metres with perfectly good results. You can get optical splitters and converters which can be used to extend a lead: I've not experimented to find out how long a lead will go before the audio starts to break up., though I would expect a coax lead to go quite a long distance if it's good quality cable.