I also meant to mention that I was reliably informed by someone who definitely knows the inside track with Ketron that the reason the X4 s are blowing fuses is that the power supply has been mounted too high in the casing and is causing a short that causes the fuse to blow. I was advised to open up the unit and put in a strip between the top of the power socket and the casing to insulate it but I ended up selling the 2nd module anyway . The first one was the faulty one and they had replaced it for me but i would always be nervous that the same thing would start happening again so I made the decision --correct decision with hindsight--to go a different route for peace of mind and reliability.