Hi Arbuckle,
Thanks for the interest in our products.
The reason why the Superclock 4/PSU are different prices for those machines is the extra time (labor) and extra mounting and wiring that is needed for the different machines. What is not clearly defined in the description is that Audio Consulting Silver wire and Cotton tubing is used for the connections (some have more wiring than others), and we have to develop custom mounting apparatus per the different machine, this takes time and parts cost. The Esound is the easiest of them all, very simple (hence the lowest price of this group), the SA8001 requires special mounting (has to be mounted in a certain location to sound the best) and much more wiring and the SA-11 uses a special Superclock frequency that is special order per project, and there is also some special mounting and prepping done there too.
I hope this answers your questions, and please feel free to contact me privately for more info on this or for some on getting feedback from our Esound customers (with their consent first) on your original question of this thread. Most (if not all) of our Esound customers do not really post here on Audiogon, but they are out there.
Best Regards,
Douglas Jesse
Reference Audio Mods