I know this question could sound like another question that was asked recently by someone else on a different topic, but I have no intention of cancelling an order with PS Audio, lol.
I know that there are headphone amplifiers that many of us connect to portable music players. But what if a portable music player already has either 4.4mm or 2.5mm balanced connections and a built-in amplifier, like Fiio M11 Pro, Astell & Kern SA700, or Sony NW-MWA1, for example. Would one still desire a dedicated headphone amp and if so, how would it be connected to the player? I know about (and have) analogue 3.5mm to stereo rca connectors. I do have an older Fiio X3 (version 2) music player that my recently acquired Sennheiser 660s connect to with the 6.35mm to 3.5mm analogue adapter.