CDP breaks and I move to computer-based...

...and I don't think it sounds as good. Am I crazy? Same DAC, but instead of CDP => digital coax => DAC, I'm running either toslink or kimber usb to a V-DAC DAC. I dunno, I just feel like the sound isn't quite "there", almost as if it is not as present, or convincing, as if it is lacking something.

The Mac outputs bit perfect, so this should not be an issue. All iTunes/Mac settings are what they should be. I am considering buying another cdp for a transport. Again, am I crazy?
Maybe, maybe not...
Computer audio isn't really as easy as "just ones and zeros".
First off, IMO toslink sucks and has always given me inferior performance over usb/spdif. USB implementations vary as well. Most likely though there is some other problem. Instead of telling us that you have it set correctly, tell us how it is set and what type of files you are using and whether or not you have tried using the cpu as a "player" and not a server by letting the disc play through the cd drive and not being ripped then played.
Did you break (lift) the cpu ground?
What mac, what os, what player (iTunes?)
What is going on in the cpu background?
Did you renice (re-prioritize) the processes using terminal or process wizard?

From what I have seen, it takes a pretty good transport to beat a server, and that something simple is wrong...YMMV
Computer is a Macbook Pro notebook with 4 gig ram, running the latest version of OS X. I am using iTunes with all iTunes processing (EQ/soundcheck,etc...) turned OFF. File format is apple lossless. In terms of background processes, I wouldn't think that this would be an issue on an OS like OS X, which is known for being stable. I have not compared playing the cd on the drive but I will try that. BTW, this setup is for my headphone rig, which may matter or not, but I thought I'd mention it.

Again, since the cdp is not functional I cannot a/b test. I am fully aware that I could be imagining a difference that is not there, or an incredibly slight one if it is. What I am leading up to is the decision to purchase a new transport, or instead commit to computer-based audio and get a Squeezebox Touch.
I would rather stick with PC audio for the convenience or access to thousands of songs.
What if you have a jitter problem? You could try an affordable re-clocker, like the Monarchy DIP, run toslink into the DIP and then digital coax into your DAC. What was the CDP you were using as transport before?
Memory and processor intensive software, like Photoshop, Final Cut, Form Z, or 3D games, etc., could affect bit-perfect audio playback, even on an OS so perfect as X...
you have to experiment (like with cd player models) what you like. Also it will only reproduce what was a good CD to begin with.
Toslink does not suck. Here is how to fix your problem, purchase a glass toslink cable and you will be shocked at the sound. Plastic toslink cables are HORRID but a good glass cable like I use is every bit as good as my $1500.00 FIM Gold digitla coax. USB has in my experience not been able to match my glass toslink. I have a mac mini with 4 gig ram and a 1TB NAS drive all connected wirelessly a d it is as good and most time better than anything knave owned in the past in including my former Wadia 7...etc
Have to agree with Audiofun here, try the Wireworld Supernova 6 glass toslink, from the CableCo or Toslink to mini-toslink connectors I think is what you would need.
I have also read that the Van Den Hul Opticoupler is very good:
The other thing you want to be sure of is that you have coreaudio set to output 24 bit. Then let iTunes worry about getting the files to core audio in the right format. TRy a 24bit download while you are at it and prepared to be blown away.
what is core audio? If it is set to 16 bit, will it still play 24 bit files? Are 24 bit files available on iTunes, and how are these produced? I think CDs have 16 bit resolution, so any 24 bit coming off of them is upsampled. What software do you use to do this and is the sound quality better than a downloaded 24 bit file?
I run a PC, just FYI. I also read something somewhere about turning off "kmixer," whatever that is. Do you know anything about that?
Core Audio is part of the MAC OS. Kmixer is windows- two different animals.

In a MAC environment typically you would set core audio to 24 bit- set and forget and let itunes upsample everything which it does well. The other option is changing core audio based on what file is being played and matching them so they are native. This requires stopping itunes, changing the setting in core audio to match whatever file is being played and then restarting itunes. All of this is done to avoid having core audio upsample or downsample which it does very poorly. iTunes ironically does it well.

24 bit files are not available in the itunes store, but itunes can play them. If you download a 24 bit file from a place like it will come in FLAC- you then convert to WAV, ALAC, AIFF, any lossless codec that iTunes can handle. Unfortuantely iTunes cant do anything with FLAC so it needs to be converted with another piece of software.
As it turns out, 4est was right, something simple was wrong: The EQ option was active on iTunes, which imparted a subtle but noticeable effect on dynamics and overall presence. This is what I perceived as *lacking* in my original post.
I have a great iMac set up feeding a dcs purcell upsampler and a dcs delius dac. I had the Ayre C5xemp CD player - a very excellent digital front end with a cavernous sound stage.

The computer-based set up I have is better. However, it should be as it cost about twice as much. I doubt if I ever buy another CD player. The big thing I noticed is that the computer server simply makes your music so much more accessible, easier to burn CDs for the car/office, and I listen so much more to my system than before.

I would've never believed that listening through a computer would sound so dang good.......