I bought a used Perpetual Technologies set-up with the Dan Wright mods and power supply -- it sounds great and does not void the warranty since the company approves Dan Wright mods. Then, I sent him a Pioneer DV-525 and the blacks are blacker and the sound is richer -- very nice work. Plus, he's very easy to deal with.
Don't know about the 9000ES, but Macm's advice and Chelillingworth's sound right. Hope that helps. Sorry I have no Stan Warren experience. I know Dan's really busy right now and asks that you e-mail rather than call, so the timing may also be a consideration.