The right headphones for the job and an understanding that, unless you employ filtering, you are going to hear hi-fidelity audio coming out of an AXE, Kemper, Helix, Headrush etc and not the reduced range of frequencies a guitar amp produces. I just revisited the HT1 schematic out of pure curiosity, and the headphones don't even tap off the power amp! So basically the guitars signal goes through 2 Op Amp stages then both halves of a dual triode, then 4 more stages of Op-Amps, then 2 more stages of Op-Amps before going into a stereo mixer (op-amp) then out the headphone plug! One one tube in the signal path of the two provided. An example of the placebo effect? Perhaps.