Agreed. I have/had portable amps and found them to be too much of a burden to carry for me. Plus having to keep two devices charged? PIA. Portability is about convenience.
There are plenty of good headphones around that don't need an amp. You also don't have to spend $2000. In addition to those already suggested Beyerdynamic DT1350 & Beyerdynamic DT770 PRO 32 will work well unamped and sound better than Beats.