Best Sonos ZP-80 Mod?

Is a basic difference between the Empirical and Cullen mods is that in the Empirical mod the reclocker is an external unit (pace-car), where in the Cullen mod the reclocker is a board which replaces a board inside the ZP-80?

"Is a basic difference between the Empirical and Cullen mods is that in the Empirical mod the reclocker is an external unit (pace-car), where in the Cullen mod the reclocker is a board which replaces a board inside the ZP-80?"

No, there is HUGE difference between the Cullen reclocker and my Pace-Car. The Cullen is an asynchronous sample-rate converter (ASRC) with a better oscillator than the stock Sonos. This is just like an upsampling DAC or a Monarchy DIP. It will improve the jitter by resampling the data, but nothing like the Pace-Car, which does not change the data.

The Pace-Car is a true reclocker with a FIFO memory that is clocked by a Superclock4. It offers superior isolation, jitter rejection and superior clock. It does not resample the data stream like the Cullen reclocker. The Pace-Car also has a separate power supply from the Sonos and many voltage regulators. It contains probably 30X the parts count as the Cullen board, even more parts than a typical DAC. This is a very complex circuit and designed to test equipment standards, using GHz coaxial cable and connectors. It can also drive I2S input DAC's directly, as well as standard DAC's using S/PDIF or AES/EBU. The jitter levels from the Pace-Car will be lower than ANY CD transport. The Pace-Car was recently compared in a shootout (I was not present) to 2 new Meridian $8K and $14K CD players and there was no contest. The participants told me that the Pace-Car was clearly better at a fraction of the price. I believe it was driven in this case by an Apple TV and an AirPort Express, but can be driven by virtually any PCM digital source.

Steve N.
Empirical Audio

If it is under 1k - I am in........ But I doubt it.
Different, more economically driven choices arisen lately.
As good as Peace Car can be, it comes down to financial decision.
But it seems that selling larger quantities works better then having a thick skin and hoping for the best. I am not an expert by any means but have seen
it work. Also onother benefit of an entery level product offered to the masses is that company is gaining future consumers, which can.... or will come back in the future , base on their earlier ( positive ) experience + products like that can finance future research or/and marketing. You will see few other products like that in the very near future. Both were talked about at the table during CES. Both analog. Both over-build and better then competition in that price range. Both for the same reason and through many conversations and planning. I also saw a similar moves from other brands - Wadia for one.
You have great product Steve but others are catching up.
We have met during CES, and you are a very good guy and I wish you well.

Thanks much for the information, Steve. It seems like an interesting product.

I have both a CD player and unmodified Sonos ZP-80 connected to my preamp via digital outputs. I ripped my CD's to my hard drive in FLAC format. I set up my system where I had a CD in the player, and at the same time the same CD ready to play via the Sonos system. I played both at the same time and used the preamps remote to do quick A/B comparisons. All I can say is the results were inconclusive. Sometimes I thought the music through the CD player was a bit better (voices and strings may have sounded slightly more present and less dull); other times I couldn't hear any difference at all.

Has anyone else attempted this test? If so, what conclusions have you found? If you've modified your Sonos with Empirical or Cullen mods, what differences have you found over a stock Sonos or your transport?