Happy owner of the FiiO E11 here. Been using it for years now ever since the release. Although my use with it is on and off, I'm overall pleased with this little device. In my area, it gets as low as 20 bucks and I have to say the functions itself worth every penny. It's small, it's light, budget friendly, comes with removable battery option and packs a punch(What more could you want). If you are starting out, personally I think this would be a perfect amp for the pick.
Had my first paring with the ATH-M50x, it was splendid. Having enough power to drive most of my mediocre headphones without any problems, connected to an android devices. Also, with a FiiO L9 cable, you can use lineout with your Apple devices which benefits from sound quality.
My setting is always off gain and either 0 or 1 for the Bass(Level 2 muddles the mids). Previously using it with my iBasso DX90 and Dunu Titan 1. It did a good job with lowering the tremble sibilant and slight fatigue I experienced with my Titan1, adds a good amount of bass texture to it and makes it smoother to listen to.
For the price, it's definitely a bang for the buck. There's also the JDS cMoyBB($35) which is worth checking out at this price range. For upgrading, I would suggest checking out the Cayin C5($145), FiiO E12A($159), JDSLABS C5($189), Headstage Arrow 12HE(EUR199) and the OPPO HA-2(£250).
Edited by Meth - 12/15/15 at 12:12am