help me make sonos better

An external dac is essential for getting high quality sound out of Sonos. But you should be aware that the digital output from Sonos is very high in jitter. Because of that, if you want to get the most from Sonos, you should either (1) select an external dac with very good jitter reduction, or (2) use a reclocker before the dac.

I chose (2). I use the Empirical Audio Pace Car 2 reclocker between my Sonos ZP and my dac. It isn't cheap (between $1250 and $2050, depending on the options), but it turns Sonos into a truly high end transport, and it widens your options for dac's.

Could you comment on whether the addition of the Pace Car is a subtle or significant improvement in the sound quality.

I think the answer to this question is system-dependent. With highly resolving components, the addition of the Pace Car results in significant improvements. With moderately resolving components, I believe the improvements would be more subtle. You can read more about my experiences with the Pace car in a review I wrote.

Also, will a better DAC also reduce jitter?

It depends on the dac. Some do, some don't. Keep in mind that the "gold standard" for jitter reduction is a FIFO buffer, which discards the timing data altogether and relclocks the audio data with a high precision clock. This is the approach in the Pace Car. Many dac's that advertise their jitter reduction capabilities do not use a FIFO buffer, but use some other approach.

I do not have the breath of experience to generalize about how much better a FIFO buffer is than other possible approaches. I can say that my Meridian G68 uses PLL's and ASRC to reduce jitter, and even with that, the addition of the Pace Car resulted in significant improvements. Again, this assumes a certain level of resolution among the rest of the system's components.

I don't know the OP's system, but since he has not yet added an external dac to his Sonos, I am now thinking that the Pace Car might be overkill for him. In that case, a more sensible option might be the Cullen mods in combination with a moderately priced dac, and a good S/PDIF cable between them.

"I do not have the breath of experience to generalize..." I meant BREADTH of experience, not some strange metaphor involving breathing experiences. :)

Bob - Yes, OP is "original poster." As for your system, it is excellent, and far better than I was assuming in my previous post. In light of that, I would say that you would certainly hear significant improvements with the Pace Car. Whether it is your best option for getting the most from Sonos is another question. I think it depends on the dac you are considering. Given the amount of jitter inherent in Sonos, if I were you, I would want bulletproof jitter rejection in my dac. Short of that, I would seriously consider a reclocker like the Pace Car.

Paul - Glad to hear you are happy with the Benchmark. Your experience with the Sonos volume control is interesting. I use the volume control on my Sonos, and I haven't noticed any problems with it. I wonder what accounts for the difference.