Hey hi yeah your amp just isn’t providing them with adequate juice. These aren’t incredibly hard to drive, but they definitely need more power than the Prime can give (at least going by the 250mW at 42Ohm number I found).

I 100% recommend you try them off a more powerful source (“more powerful” doesn’t necessarily mean more expensive btw. Lots of great options under $1000 or even at the $600ish mark) before selling them for the hd800. They’re incredibly detailed and great for mixing and mastering. And if you want more bass, you’d be surprised at the difference those bass ported pads will make (is it worth $250? Idfk that’s pretty wild lmao).