(At time of purchase) nowhere on this product page, nor on their website, (nor anywhere!) could I find a statement that this phono preamp supports moving magnet. So, I called them and wrote an email. Guy on the phone at Rolls/Belari in Utah stated it would work with moving magnet, but NOT with moving coil cartridges. He went on to say "I don't think we make anything for moving coil." I got an email response from them a week later stating the same thing: "The PA550 only works with Moving Magnet, we don't have anything designed to work with a moving coil cartridge."
So, there you have it: this is a moving magnet phono preamp.
I am using this on the U-Turn Orbit turntable (no built in preamp) with a Ortofon OM5E cartridge. Stock U-Turn RCA cables coming from turntable directly to phono in RCAs. I tested the RCA and headphone outputs with my Audio Technica wired headphones and it sounds fantastic. I also have a bluetooth transmitter hooked up to a JBL Charge 3, and it works great, clear sound.
You have to ground it! In my setup I got the ground loop hum. The Orbit Turntable does not have an exposed or accessible ground post, so I did some googling and discovered people grounding the preamp to a coax post on a outlet extension (such as Belkin and Monster make.) Ground loop hum went away! ******Though, I did try this with a Furman PST-2+6 Power Station and the coax posts on that unit apparently are separated/isolated from the same ground as the plugs for the turntable—this resulted in no change to the hum. In short: you have to ground it to the same place as your turntable AND amp. Plug it all in the same outlet.
The build on this unit is kind of insane. Super thick cold rolled metal with knobs and switch that are some of the most solid feeling things I have ever used. There is no play or jiggling with these, nor the posts and jacks!
Worth every penny. I high recommend for your turntable with moving magnet cartridge.