Bye bye CD player. I enjoyed listening to my Thule CD player a lot and I’m sure the new owner will enjoy it also. My new setup however sounds even better and I have all my music at a touch of a button. Lets call it progress.

I have had a Apple AirPort Express for some time. The interesting function is that it can stream music from iTunes to the stereo, something Apple calls AirTunes.

Connecting it to my amplifier via the analog line out works well but the sound is not Hi-Fi quality. To get that you need to use the optical digital out to a DAC.

Home cinema amplifiers usually comes with one or more digital inputs but two channel amplifiers, what I’m interested in, does not. My old English preamplifier certainly has none. A dedicated DAC to place between the AirPort and the amplifier is what I need.

I tested a couple of DACs from my local audio shop. When the turn came to the Musical Fidelity X-DAC V3 I stopped testing and just enjoyed the music. My stereo has never sounded better!

Now I have a stereo ready to receive music from my computer and play it back with a wonderful warmth and presence. What should I feed it?

During testing I only used the Apple Lossless format. Since it’s a lossless compression format full audio quality is preserved whiles reducing the file size with something like 40-60 procent.

The Apple Lossless files is still big and my MacBooks harddrive needs to have room for more things than music. MP3 is the most common compression format but for my ears AAC sounds a lot better at the same bitrate. Not a big surprise since AAC is a modern format, part of the MPEG-4 standard.

Marc Heijligers has made a comparison between compression formats at different settings. It interesting but in the end you have to trust your own ears.

With AAC encoding at 256 kbit/s I can not here any difference to Apple Lossless, i.e. full CD quality. Going down to 192 kbit/s (+VBR) was only sometimes noticeable, but not more than that. For a lot of music, especially if you mostly play it in the background, AAC 160 kbit/s is ok. Below that is of no interest to a music listener.

When I have the storage to spare I will go with Apple Lossless but for now I have settled on AAC 192 kbit/s (+VBR).

Interesting altarnatives to Apples AirPort Express is Slim Devices products Squeezebox and Transporter. They stream music just like the AirPort but have displays and remote controls.

Can music streamed from a computer ever sounds as good as that from a top end CD transporter? Personally I believe the answer is yes. The only weak link I can think of is the ripping of the CD to the harddrive. I’m interested to here readers opinions on this.

For people interested in solutions like this I recommend Stereophile Computer Audio section. Other reviewers of the AirPort Express only briefly mentions the function to stream audio to your stereo. Stereophile briefly mentions that it can be used to set up a wireless network and then spend the rest of a long article to talk about sound quality.

Update 2010-11-08: With iTunes 8 and later Apple has unfortunately broken the optical out on the AirPort Express, see link to discussion below. I now have a Mac Mini connected directly to my DAC instead. A separate network drive contains all my music in Apple Lossless format as well as my DVD collection ripped with HandBrake.

Update 2010-12-19: The just released 7.5.2 Airport Express firmware update finally fixes stutters and skips with the optical out. About time Apple, it only took you two years!

Airport Express: Optical out: Itunes 8 skips, 7 works, Airfoil still skips