I understand that there are Apple products out there but I am familiar with the SqueezeBox Touch which does this very well.
I use a Mac Mini connecting to an Apple Airport Extreme (you use about any wireless router). Then I have a Thecus NAS wired to the router. I store my music on the Thecus and have ITunes pull the tunes wirelessly from the Thecus. This is a little pricey.
If your Mac has means to connect to your preamp, amp or dac,and has wireless capabilities, you can use just that and connect a wireless router to your cable modem.\
Does that make sense to you ?
Another common way to do it is to stream to an Apple Airport Express then connect the mini-Toslink digital output from the AE to the optical input of an external DAC. Even a used 802.11g previous-generation AE is plenty fast enough and can easily be found on ebay or craigslist for under $50 if you're interested in keeping the experiment inexpensive.
Of course you need to have a DAC or a player of some kind with optical input, which can cost anywhere from $50 to many thousands of dollars.
As suggested, an uncomplicated approach is the Squeezebox Touch.
A very simple way is the use an Air Port (AE) express and itunes as Sfar recommends but you can connect it directly to one of the inputs on your pre-amp and use the DAC in the AE. The DAC of course isn't the best on the AE but does a pretty decent job for what it is. You can then evaluate if you want to go further expense wise. I currently stream Radio Swiss Classic using an AE to my stereo system and it works great.
From what I am understanding thus far, the word DAC keeps popping up. I have Air Port on my IMac, but from their just a Rega CD player, pre-amp and my amp.I would think that their has to be something from the Air Port comm. to my pre amp with RCA jacks. Which must be the DAC that is mentioned.. Correct?
I'm tech-challenged but was able to set up a system that I'm extremely happy with. Bought an Apple Time Capsule with 1T of memory for storage/router on which I've saved my 700 cd library using iTunes in lossless format. TC streams music to a Zardoz (French modified Airport Express) which I have wired into my pre downstairs in my listening room. Bought an iPod Touch to use as a remote. Still have my Arcam FMJ 27T cd player in my system, but not sure why. Once you get set up, you'll never want to go back to manually feeding your cd player!
2nd the AE or AppleTV (ATV!)
you do NOT need a wireless router when using MAC. I run my AE as a 'client', which is a dead end connection.
I use my iPod Touch as 'remote'. You can even listen to internet radio, though I'm still trying to figure out how to select a URL for the station....I'm currently limited to those stations which are listed in iTunes.
Be careful in DAC selection and try first, if possible. My AE simply puts out something which my CA840c, used as DAC, does not like. I went back to the less good analogue connection.
Difficulty? 4 on a 10 point scale. Running the Airport Utility is easy and all I do to turn it on is enable my computers airport. Connects right up.