Variable Loudness DIY for Noob?

[freon2]

The Decware ZROCK3 is kind of like a loudness miracle box but its over 1000$.

 

[jjasniew]

Decware ZROCK3

"There is no power switch. It is left on 24/7 because it uses lower voltages to keep the tube from getting hot".

Let's one wonder if this $1000 contraption runs the tube similarly to all those "tube" DACs, ART "tube" mic preamps and compressors?