Need help for my longterm to end game closed back portable headphones. i have a simple gear which consists of Fiio m11 topping nx3s amp . may upgrade gear gradually ( xduoo 05 plus . m15 waiting for discount or opportunities) but wanted to start off with Headphones. Headphones in my...

I was looking for a good pair of high grade headphones, and I recently saw two pairs of HP-3 going for $600 (they are used but well cared) https://audioadvisors.com/closeouts/ Is it worth getting it and what does these headphones compare to other similar priced ($600) dynamic headphones?