asynchronous USB dac or jitter reducing device

I have a Red Wine Clari-T driving a huge single driver baffle. The range is roughly 80hz to 15k. I am interested in a macbook based digital system using Wifi or usb. The only piece of the puzzle I have is the MacBook. My budget is less than 1K including airport express or other similar, an asynchronous USB dac and or a DAC and pace-car type reclocker for jitter. If I have an asynchronous USB dac do I need a separate device for jitter? The Pace-car is clearly out of my budget, so what are my options?
Thank you in advance.
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2nd Benchmark DAC. I use it with MAC-Mini/Airport Express. Stretch your budget by $150 and get AE ($150) and new Benchmark DAC1 ($995) to obtain 5 years warranty and avoid problems that early Benchmarks had (thin sounding op-amps, high output impedance on unbalanced outputs).
Try an EMU 0404 - with balanced outputs - $185 does the job, sounds great. Yes, audiophiles will not like the plastic case but it works.
I can appreciate that some of the less expensive DAC's listed above are good buys. However unless you can reduce the jitter you probably won't be happy with the sound quality. Take a look at the Benchmark DAC1 USB. It will reduce the jitter and the USB version has their best OP amps. Should cost $900-$950 used here on Agon.

There may be others as well, but the jitter reduction is worth the investment.

Paul is right - used USB version will not only guarantee later version without problems I mentioned before but also better op-amps in the output stage and therefore lower output impedance on balanced outputs. It just happen that best jumper setting for me is -10dB and I don't want to use it because of very high output impedance at this setting. Newer op-amps are stronger (LM4562) and divider is different. Also USB gives more flexibility.
FYI, The EMU has an async USB interface that reduces jitter and compares favorably with other expensive USB DACS I have listened to.
With asynch USB the only jitter you have will come from clocking the data from the USB data buffer in the DAC "box" to the DAC chip itself. There is no clock recovery or clocking of data from the source to the DAC "box" similar to what's done with S/PDIF. Excellent white paper about all this on the Ayre site.
Straighten me out as needed everyone. My understanding is that jitter reduction methods in DACs and whatnot reduce or eliminate the jitter added in that component. If you get jittered data coming in from outside you cant do anything about it. If this is indeed correct that implies that you cannot added a separate device to reduce jitter.
No, they reduce all S/PDIF jitter (transport, cable etc). They cannot reduce jitter of their own D/A clock.

There is also jitter in A/D process - that one cannot be removed. Poorly digitized tapes at the beginning of CD have to be digitized again (with better clock).
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