As to if you should get the Stax or the new source. If you get the source now, will you be able to get the Stax at a later date? If so, I'd vote for the source first. If not, get the Stax now.
As to my impressions of the 303 vs. 308. The 303/200 is a more substantial machine, at 35lbs, with balanced outputs, chip based upsampling, and an aluminum tray. The 308 goes 25lbs, no balanced out, software based upsampling, and a plastic tray. They both have the Cary house sound, smooth, detailed, but ultimately revealing. They will not coverup faults in the recording medium. My opinion has changed on the relative sonic merits of these over the last month or two. I'd say that the upsampling is better on the 303, and it is simply a more musical sounding player. That said, I now think the 308 is about 85% to 90% of the way to the 303. At about half the price, that has to enter into any consideration of purchase. I got my 308 for about $1,200 from Kevin Deal at Upscale Audio. You may get a better deal from a different dealer, depending on your negotiating skills, or previous purchasing relationship. And as you've said used units may be available as well.
BTW I've used my 308 with a Stax 303/SRM-T1 system, and the sound is something special. I'm hoping to get my SRM-T1 modded or I'm going to find someone to build me a Gilmore Electrostatic Special for even better performance.
