Why some preamps weigh 50+ lbs?

Mine weighs 53 lbs and has two chassis. It takes 8 tubes and a lot of space. The mono amps each weigh 45 lbs and have 7 tubes each. Looks cool and sounds pretty good. One thing for sure is with 22 tubes it’s one heck of a good space heater ! This way I can hear my electricity being used. I just wanted to inject some humor. Happy Thanksgiving to all, Mike B. 

I asked that question when I got an All Clad copper core sauce pan, when I compared it with my Hexclad pan. Stopped after using it for the first time. 

Crap, my preamp only weighs 49.999lbs - better look for a increased weight=sonic upgrade 😉

@kennyc - put some audiophile approved brass damping weights on the top, carefully reweigh, problem solved.

I am on the verge of buying a preamp that costs $433/lb.  But after reading this thread, I probably should look for something with a higher cost per pound?