I have not had two great head-phone amps in my audio life.
My first was the legendary Melos SHA. Used to listen to them with a few different Grados. I sold it about 10 years ago. If I found one used, I would buy one again for its amazing sonic abilities.
Recently, in March I bought myself a Eddie Current Balancing Act and the Audeze LCD-2. This is definitely on the higher end of what can be achieved sonically in the headphone listening world.
If I can sit and listen to music and not feel any desire to be anywhere else than just be and listen to music, then I am having a musical moment, like being in the pocket. I have many musical moments with this setup when I just sit and let the music come over me.
But, now I also have a small tube amp and speaker setup that gives me a whole different type of musical experience. And I am tempted to expand my speaker system, but it surely is going to get quite expensive both in space and money to achieve that kind of musical experience.