I was wondering if anyone can help me determine about how old my 400+ is. I'm pretty sure its from the first few years it was made. I know the newer ones have the power cord that can be detached, I don't have that, mines permanently attached. Also, I think the newer ones have a 7 band parametric EQ, while mine only has a 6 band. If someone has the ability to look up the serial number and tell me the exact age, that would be great, but if someone could tell me approximately how old it is, based on the info i posted, that'd be very helpful. Thanks Also, sidenote, I just got my amp back yesterday from when the bias was having problems. It was only in the shop 2 weeks, but i missed it, having only a headphone amp in the interim. Its working perfectly now, and I have my sweet sweet tone back.