So I ordered a presonus bluemax compresser off ebay... my first used piece of equipment. At $55 including shipping one would figure you can't go wrong. Well it did. I recieved the unit today... it powers on fine and everything, however, the compresser kicks in and out on its own. Seems like there is some lose wiring or connections. 15% of the time it is working properly. The rest of the time it is just adding unwanted noise into my signal. I'm going to try and email the seller although I doubt I will get anywhere. Looks like I am out $55.