I'm in the process of buying a headphone amplifier, my headphones are the HifiMAN HE400se Stealth Edition.
The Topping L50, A30 PRO or L70 are currently on the short list.
My signal chain looks like this: RME Baybface PRO FE -> headphone amp -> GENELEC 8030C
The A30 and L50 have pass-through...