My office setup

I recently put together a small office system and I'm trying to get the best quality of sound when I play music from my iMac Intel Core 2 Duo computer.

I am currently playing my music wirelessly through my AirTunes and then running a monster cable to my Parasound Halo 3 preamp. From the preamp, I'm using a couple of Mogami balanced cables to go to my two Quad 12L active speakers.

The sound is ok, but I have been noticing some distortion, even when I'm playing Apple Lossless files. I was wondering if anyone knew how to maximize my sound quality with this setup. I am not looking to buy a lot of extra components, but I just wanted to know if there was an easy fix to this problem?
If I understand your description correctly, you're going wirelessly to an Airport Express and then using an analog stereo-mini to dual RCA cable to connect to the preamp, is that correct?

If that's it, the weak link is that you're using the internal digital to analog converter in the Airport Express. It would be much better to use an external DAC with a Toslink input, connecting to it with a digital Toslink cable from the same port on the Airport Express. Then the analog outputs from the DAC would go to your preamp.

Virtually any external DAC you can buy would be a big improvement over the tiny chip in the Airport Express. Finding a used DAC or one of the inexpensive imports on ebay would be a place to start.
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Thanks guys. You are right Sfar, I am going wirelessly to my Airport Express. I didn't know that it had a internal DAC. I will look into getting an external DAC. Do most come with this Toslink input that you're referring to?
The signal that's being sent from your Mac is a digital signal so it has to be converted to an analog signal somewhere along the way. The Airport Express will do it for you but it was not designed as a high-end audio component and it's much better to hand that task off to a device that is designed specifically for it.

Most DAC's do have a Toslink input, but not all, so check that before you buy something. The same stereo-mini outlet you're using now for analog output will also accept a Toslink cable with a mini-Toslink connector, or you can use a standard Toslink to mini-Toslink adapter on a standard Toslink cable. Most DAC's that accept Toslink will use a standard Toslink connector on that end. So, you'll need some combination of cable and/or adapter that gives you a standard Toslink connector on one end of the cable and a mini-Toslink on the other.

A search of the site will probably give you some good information about DAC's to investigate.
I'd completely agree with Sfar regarding making an improvement in the digital conversion (the DAC in the AE leaves a whole lot to be desired). But if you are hearing "distortions" I wonder if it isn't the amp(s) in those active speakers? Why are you using a preamp? Have you tried removing the preamp and going straight to the speakers (I'm assuming they have a volume control)? Usually active speakers do not require a preamp in between to boost the signal. Regardless, an external DAC will likely improve things, though I'm not certain it will get rid of the "distortions" you are hearing - can you expand on that description?
Jax2 is right, I should have been more thorough in my response. The sound of the analog output of the Airport Express isn't nearly as good as using the digital out to an external DAC but you shouldn't be getting anything I would describe as distortion. Isolating what's causing the distortion before you spend money on a DAC would be a smart move. I've
Ok, I think that makes sense about trying to go directly from the AE to my active speakers. At least I can see if that takes care of my distortion issue.

I got the Preamp in the first place because I also use my office system to records on my Rega P3 (Rega P3 > Bellari Phono preamp > Parasound Halo 3 > my Quad 12L actives). I added the Parasound because when just using the phono preamp, I wasn't getting as full a sound as I wanted, especially in the low end. Records sound a lot better now that I added the Parasound to the mix.

I'm pretty sure that you could také the preamp out of the loop in both scenarios. With your P3 just use the phono pre directly to your active speakers. Most active speakers have a pre section or some sort of attenuation already in them. Try it and let us know if the same "distortions" are there. I'd still think about going to an external DAC regardless. You should also avoid using the volume control on your computer - either disable it or turn it to full and use the attenuator on your speakers to control volume.
So I've taken the Parasound out of the equation. I gotta say, that I really didn't need it. The computer sounds better, and the records sound just as good as they did before. Only problem now is playing records and then switching to play stuff from the computer. I've got two different sets of cables that I'm going to have to plug and unplug accordingly. Any thoughts in that area?