I use the classic wirelessly with no issues. I use the digital outs into the DAC of my Opus 21 and it sounds great.
As to the jitter issue, there are as many opinions about jitter as there are products that claim to reduce it. I use a Monarchy upsampler between my Sqeezebox and DAC and its effects are nominal if at all. I have been intrigued by the Pacecar and would like to try it, but I remain a bit of a skeptic and the Pacecar is not a cheap experiment. I tend to believe that jitter is not a huge issue with modern reputable DACs, but I remain open to any evidence to the contrary. If you try it, please report back with your opinions.
As to the jitter issue, there are as many opinions about jitter as there are products that claim to reduce it. I use a Monarchy upsampler between my Sqeezebox and DAC and its effects are nominal if at all. I have been intrigued by the Pacecar and would like to try it, but I remain a bit of a skeptic and the Pacecar is not a cheap experiment. I tend to believe that jitter is not a huge issue with modern reputable DACs, but I remain open to any evidence to the contrary. If you try it, please report back with your opinions.