Is your audio being driven out through ASIO or USB ?
If USB - then why not simply use a portable USB DAC which has a built-in headphone amp.?

There's hundreds of brands & models to choose, but FiiO, HiFiman, Oppo, Dragonfly are some quality starter brands, each have many models.

 

How about the second-hand market for the original Babyface? There must be a few people upgrading. The low latency on RME stuff is stellar, not to mention reliable.

 

If you make music with your computer,you need absolutly a good soundcard.
But the choice is not only depending on your needs of inputs,but your budget,too.
For very good performances and a medium price you can get the Native Instruments Komplete Audio 6,or the Steinberg UR series.
If I were you,I would buy for sure a Universal Audio Apollo twin soundcard, I think they are top of the notch,and with these you can access to the famous UAD plugins !!!
Personnally I have a RME UCX which is expensive but awesome!
I had a RME Babyface,which sounds very good but its quality is bad bad bad...I have had two failures with it !

 

ASIO is an audio driver for DAWS.All soundcard made for musicians have a ASIO driver.
And USB soundcards have a headphone amp,which is better in quality with the price rising of course.

 

For an interface dedicated to just headphones I would say a Focusrite VRM which you ought to be able to find for peanuts (Also it a really cool little device for messing around "re-amping" things through the DSP which it comes with for some creative fun and also practile mixing).

For a proper interface that is compact but top notch then I'd say Audient's iD14, The value for money is about as good as it gets and the performance is easily on par if not above that of the oh so praised (and rightfully so) RME portable interfaces, The thing it doesn't have mind is the internal mixing/routing software that you get with RME products but what it does come with along those lines is (Audient Mixer app) is very, very respectable. it is well worth the asking price, The mic preamps are the same as you get in their consoles which not many top-notch designers/marketing people would dream of, A superb DI which I won't rattle on about but will just say that it is on par to some DI boxes i've used over the years costing far more than the actual interface does and the headphone amplifier is a good quality one (If that wasn't enough it also features an ADAT or SP/DIF input that enables it to expand to a 10 input interface!), The conversion is fantastic also with TI/Burr Brown taking care of things: https://audient.com/products/id14 £189 is what it'll set you back. I've heard it alongside an apogee duet, RME babyface and a few others and well for me/my personal preferences it was the winner

Anyway you can't go wrong really with the quality of anything mentioned above by fellow members, I'll totally conceed the iD14 is not as compact as the duet or babyface and the selling point is not specifically its headphone amplifier either

Hope that it helps/Is of some use, All the best to everyone as always

 

Heard great things about Audient. The Audient id22 has just been reduced in price ... might have to snag one for the road...

 

my go to on location interface or travel interface while in hotel rooms is a TC Twin, great little interface. will soon be replaced by an apollo twin