I've been using the Simaudio Moon 310LP preamp for several months and I love it. I upgraded from a Heed Quasar, which is a wonderful phono pre on its own, but the Simaudio is definitely a few rungs up the ladder--more detail, air, presence, life, you know, all the things that make recorded music sound more "real". The gain and loading options are generous and probably all you would need for most cartridges. I purchased it together with the power supply, and I couldn't image using it without one. I did an A/B comparison with and without the power supply, and without it the sound was comparatively anemic and lacked authority and body. So, basically, I think the power supply is essential. Highly recommended phono preamp!