Why some preamps weigh 50+ lbs?

@mofojo "Why some preamps weigh 50+ lbs?"

please ask specific preamp manufacturer!

While not exactly 50 to 70 lbs, my purist preamps, yamaha C5000 (~42 lbs) & luxman c900u (~43 lbs) are not exactly lightweight gnat farts either...

I am increasingly convinced that the yamaha is the best sounding out there, not to mention it is a work of art.

I have also seen some cost no object eurocrap that is just foolery when you actually open it up...the weight alone doesn't mean much.

Owner not leaning on the scale, right?