depends on phones, but it won't hurt. also, judging from the fact that you have some pretty expensive buds, something like a schiit magni 2 for 99$ won't hurt your wallet so much and you are pretty much guaranteed to have NO requirement for other desktop amp. if you wan't portable, I'd just get a good player with good amplifier built in (I use iBasso DX50 for example).
as for the necessity, it depends - depends if you want to get sound from your phones or want to use their full potential. by using their full potential, I mean almost any phone will benefit from an amp that has heaps of headspace and power. all I can say my phones sound better out from my DX50 compared to headphone out on my pc...