Life is complicated, lets keep it simple.

Get the small Airport Express from apple and you will be up and running in no time....send music wirelessly from your Mac pro to your existing gear.

It can't get any simpler then that. Plug it in (connect the audio to your amp with a 1/8 inch stereo to RCA adapter), use your airport assitant to set it up, launch iTunes and off you go.

As for formats and hard drive space. I prefer lossless compressed music rather than lossy formats although the differences are not always readily apparent - so don't let this stop you using iTunes and buying tracks from the apple store.

Hard drive space is getting to a competitive level with stacked CD changers. I use four Mega changers. A CD mega changer costs about $1 per CD of storage. Alternatively, 1 Gb of hard drive storage space costs roughy the same (you need roughly 1 Gb per CD of storage in order to have backup space as an umcompressed redbook CD takes roughly 500 to 600 Mb). I would suggest to use a RAID drive system or mirrored drive system with multiple hard drives to ensure backup. Five years ago when I built my system around Mega changers, the hard drive option was much more expensive...now I think hard drives are very competitive.

If you are a serious SOTA audiophile then you could try sending digital out to a DAC of your choice (rather than use the DAC's in the Express) or go for a SOTA slim devices transporter, which by all accounts uses some of the best DAC's in the biz.

G'luck

Simple is the keyword. Airport Express would be the way to go for you as Shadorne sugests, but you would need a decent Digital to Analog Converter (DAC)for acceptable sound quality (wireless signal from Mac Pro to Airport Express, optical digital cable from Airport Express (it has analog outputs too but not of audiophile quality) to a DAC.. and there you go, playing directly from iTunes in the computer. I would also recommend apple lossless... rip cds with the error correction checked. If you hesitate because of space requirement, you can get external USB hard drives for more space... price on these is really comming down. Good luck!

I would reinforce the advice you got from Shadorne. A variation of the MacBook > iTunes > Airport Express > amplifier is what I use and it doesn't get much simpler.

As he said, the next step up in quality would be to insert an external digital to analog converter between the Express and your amp. Even an inexpensive DAC like the Lite Ah for @ $150 would be an improvement but the simpler setup will sound better than most people expect.

It's easy and relatively inexpensive to try it and see how it works for you. The Airport Express is $120 and works extremely well as a wireless access point for the Internet, even if you decide not to use it for music. A decent cable is about the only other thing you need to get started.

The MacBook Pro has a large enough hard drive to store quite a few CD's, even burned as Apple Lossless files. You'll have the original CD's as backup so you don't need to worry about an external drive until you've got enough music to begin to crowd your internal hard drive or you start downloading enough music that having a backup becomes important. By that time hard drive storage will be even cheaper.

There are some people here who will tell you they can hear a difference between Apple Lossless files and other formats, and I don't doubt they can, but for most people, with most systems, the difference isn't audible. Even if you're one of those people, the difference may be important to you for only a few recordings.

Once you get set up the convenience is addictive. I find myself listening to a much wider range of music because it's so much easier to avoid the habit of just reaching for the same CD's over and over. Playlists are a wonderful bonus, as well.

I second Sfar and Arni. The only problem I have found is disc storage space. I have a 500 gb external via firewire to a mac>express>Audio Research Dac>integrated and I haven't looked back. It's amazing how quickly it fills up in uncompressed formats. Again, the only problem I have found is when your library exceeds the space available on ONE hard drive. Adding an additional hardrive is simple enough, but getting itunes to use two different hard drives for a single library becomes tedious and bothersome, unless someone else has a any ideas????
I also have the Slim Designs Squeezebox, which gives the option for coaxial digital output to a dac, but I prefer the functionality of the express controlled by a computer. The remote is convenient, but sometimes the device locks up and doesn't stream from the host computer as well as I would like, causing the music to skip.

At risk of sounding like a broken record (pun intended), go the Apple route most are advising here. I'm not crazy about the wireless Apple Express solution though. I ended up liking the sound of a hard-wired (USB) direct connection, rather than wireless. Nevertheless, if you DO go wireless for convenience, definitely use a good DAC with the AE (conected via Toslink - you'll have to get a special cable for that as it's not a standard toslink on the AE side). Alternatively you can get a USB DAC that connects to your MacPro, or an interface that converts USB to S/PDIF and then go to a DAC. The Waveterminal U24 is such a device that I used and liked very much, but it is no longer available new.

Simple answers to simple questions:

1. Yes, store you music on a reliable external hard drive. In general, storage is very cheap relative to the audio world. You can get a 250 gig drive that'll hold quite a bit of music for just over $200 (or less if you get a cheap drive). An iPod is not a good alternative because it requires you use the less than desireable little DAC in the iPod, and or the opamp in there. Do not use the iPod to store your library, though it is a great mobile listening device if you're on the road. Also you cannot transfer or burn any tunes that have been stored on an iPod as far as I know. Keep the tunes on a hard drive. Back it up if possible as hard drives can and do eventually fail. No, this does not effect the quality of the sound if you've ripped the music the right way.

2. In iTunes choose either WAV or Apple Lossless. The former will render a file about twice the size of the lossless file so will take up more space. Apple Lossless is, by all reports, truly lossless. I have not been able to tell the difference in comparing the two. In lossless you could get about 400+ CD's on a 250gb drive. If you want to check with your own ears (and I'd advise this since you are looking for the Grail), rip the same CD or tune in both formats and play them back to back. I'd be curious if you, or anyone else can tell the difference.

Have fun.

Marco