Perpetual Technologies P1,P3, and Monolithic PS

What is the deal with all of these units on Audiogon? I have this setup, and it is by far the best D/A combo I have ever heard for anywhere near the price!! I used to work in the business, and we had a lot of high end gear. The differences between this combo and the high end CD players or DAC's is very miniscule. There are even posts up for all three with a price of $800! This is the bargain of the century! I am wondering if people are using inferior transports, cables, preamps, amplifiers, or what?? If anyone has these units for sale, or have sold these units, please let my know the reasoning.