iBook is dead quiet when streaming music. Like all laptops it does get hot when doing intense processing. Heat is definitely not good for computers, and this is a drawback of laptops. I do not know if it's a better or worse means of streaming music than the other choices. I can tell you that I've had some strange digital artifacts happen when ripping on my laptop, which do not occur when ripping the same CD's on my tower. This has happened on about 3% of my rips and I have been to the Genius Bar for a Mensa Martini and still have not figured out why. I'd venture to say the MacMinis get quite hot also, and the iMacs marginally less so. Anytime you put that much computing power in a small container it's going to get hot. Towers have space and cooling fans and do the best in that regard, but are also generally the noisiest. Streaming music is not a processor intensive function and when I do use my laptop to stream (only) it does not get very hot. If I am doing other things on it, like running Photoshop at the same time, it does get hot. If you have your library on an external hard disk you can use any computer in your house to stream music as long as that computer has itunes (or whatever software you use on it). Bruce_1, there are plenty of threads on which USB DACs are best. Personally I think the Pardisea+ has huge bang for the buck and is a wonderful solution. As far as a USB conversion interface I'd say its a strong bet that Empiricals stuff will be a great way to go and will likely be a step up from the HAG USB device you're using (as I said, I didn't have good results using my friends version of that device...YMMV). I find it very hard to believe, based upon what I've heard trying the Airport Express, that any DAC would make a digital stream coming out of it acceptable for critical listening. It sure did not sound good with the various DACs I've tried it with (Benchmark, Muse, CAL). Which brings me back to that computer digital to SPDIF conversion - I do think it makes a very significant difference what devices is actually doing that conversion, and whatever is in the Airport Express is not doing it very well evidently. I think there are devices that Empirical and Wavelength make that convert USB directly to an I2S stream which is somehow a better method. Look to others with more knowledge on the subject to explain why, or just write to Steve Nugent or Gordon Rankin. Here's the Wiki on I2S:
I²S
From Wikipedia, the free encyclopedia
I2S, or Inter-IC Sound, or Integrated Interchip Sound, is an electrical serial bus interface standard used for connecting digital audio devices together. It is most commonly used to carry PCM information between the CD transport and the DAC in a CD player. The I2S bus separates clock and data signals, resulting in a very low jitter connection. Jitter can cause distortion in a digital-to-analog converter. The bus consists of at least three lines:
1. Bit clock line
2. Word clock line (also called word select line)
3. And at least one multiplexed data line
You may also find the following lines:
1. Master clock (typical 256 x bitclk)
2. A multiplexed data line for upload
[edit] Normal I²S
I²S consists, as stated above, of a bit clock, a word select and the data line. The bit clock pulses every time new data is placed on the lines. The bit clock will operate at 64*samplerate. So, for example, CD Audio (at 44.1kHz) will have a bit clock of 2.8224MHz. The word select clock lets the device know whether channel 1 or channel 2 is currently being sent, since I²S allows two channels to be sent on the same data line. Transitions on the word select clock also serve as a start-of-word indicator. Each channel can transmit up to 32 bits, so it is easy to see that the word select clock will operate at a frequency equal to the sample rate.
I²S data is sent from MSB to LSB, starting at the left edge of the word select clock, with one bit clock delay. There are also Left Justified I²S streams, where there is no bit clock delay, and the data starts right on the edge of the word select clock. There is also right justified I²S streams, where the data will line up with the right edge of the word select clock.
I²S signal can easily be transferred via Ethernet-spec connection hardware (8P8C plugs and jacks, and Cat-5e and above cabling).
