I've been browsing here for a while and used all of your excellent recommendations to build a home rig that I'm very happy with and now my office setup needs some updating. At home I have Fiio e10 -> Little Dot MKII -> HD650 and at work I have Fiio E17 -> O2 -> Cosmic Ears HY3 / Beyerdynamic DT770 250 ohm.
To my ears my dt770's are lagging a bit behind the HD650 and HY3's quality-wise, and while they're good headphones, I'd like to see if it's possible to get something a bit better.
I work in a quiet office so open-back is absolutely out of the question, and I really like the HY3's so IEM's are out too, leaving closed back. My budget is $300 and it would be nice if whatever headphones I got would pair well with my O2 amp, since I don't want to replace it right now.
I've been leaning towards the Mad Dogs by MrSpeakers, though I'm unsure if the O2 can adequately drive them.
So send me your recommendations and gold nuggets of experience! Would the MD's pair well with the O2? Or should I look elsewhere?