So, thru happy circumstance, I just came into a pair of old Langevin AM-4 channels, pulled off a board long ago. What I've got is just the pres, mounted up with nothing but a power switch and a switchable (20db?) pad. They apparently hadn't even been turned on in 10 years -- power cord gone, had to make one of the 4-prong xlr things to even power it up. Here's the shocker: not only did the pres fire up, they sound, well, real good. Really quiet, strong, absolutely no apparent problems. Beyond general gear-lust chitchat, I really don't know the first thing about vintage electronics. I sort of have the idea that there's a meaningful shelf life for a lot of the components, and that at some point this stuff just shouldn't work. I also don't know much about the AM-4's, except that they're, um, well-regarded and Manley has the rights to the name. What should I know? Any info about the Langevins or old electronics generally would be real welcome.