Why some preamps weigh 50+ lbs?

There's much more to a preamp than a Wiim streamer. 

It’s all about the use of top-shelf premium quality components parts in a premium layout / design, including inter alia, the. use of massive and heavy power supplies required for premium audio performance.

For example ,

- my REGA ISIS VALVE cdp weighs 55  lbs ,,,, not your typical cheap build big box store offerings,

- similarly,  my REGA OSIRIS integrated amp weighs in at 58 lbs,

My BAT phono pre weighs 36 lbs.

Makes me feel better about how much I paid for it!