Amplifier for headphone

[Jolaff]

Where to start...

I have some DT 990 Pro 250 ohm headphone plugged into an Audient iD14 audio interface that is plugged into my MacMini via USB.

I never have to set the volume to maximum for my headphone but I'm not to far from (the max).

I recently tried my headphone at a friend's home in a home theater amp and I felt my headphone to sound better than usual. I don't know if it was only in my head...

That bring me to think that maybe I should buy an amplifier to drive my headphone...

How much should I pay ? Do you have one to recommend ?

Also, I though that I would have to add the amp in my chain between the headphone and the Audient. But when I look at something like the FiiO K7 amp, it looks like I would have to plug the amp in the computer via usb, which would mean that the amp literally replace the audio interface ?

thanx...

[BertKoor]

A good diy headphone amp kit (eg CMOY) is maybe $15 in parts. Ready in a box: over $150 because target audience is audiophiles with more money than sense.

When plugging in a headphone amp into usb, is that for power only, or does it function as an audio interface? The owners manual should explain...