Rightly or wrongly discarding the DAC and headphone amp I chose is not a financial option. Secondly here is some 63 year old thoughts.
Firstly might equalization help with whatever hearing loss I may have?
Secondly does the old theory of tubes clipping more gracefully the dynamic high peaks in the music still hold sway? I do not know if relatively low-power headphone amps are subject to power amp theory, but I thought may be they are.
EQ can help, isn't that part of what a hearing aid does.
Forget about clipping, that should not be happening, get an amp that has enough headroom. This is easy enough to do nowadays. The old theory is not old theory but soft tube clipping is for an electric guitarist not for someone trying to enjoy listening to music (playback). If you opt to buy a tube amp it's not for the purposes of clipping but for the sound of tubes, being even order harmonic distortion, not a lot of it, just a bit for warmth. Myself, I prefer the clean sound of Solid State, but that's a personal choice. I do have a small hybrid amp.