iamknDACs are like headphones, subject to own preference. Having said this, quite a fan of the FiiO Q1 II as a portable DAC and the FiiO K3 as a desktop DAC. Both are around $100. In the same price range, the Audioquest DragonFly is also an option. I don't have one myself, but people talk wonders about it.
Sub $100, take a look at the FiiO Q1 (old gen), FiiO K1, FiiO A1 or Nuforce uDac. Again, I haven't tried any of these but are frequently recommended as first or "inexpensive" options.
asierThank you so much for your suggestions! What do you use your FiiO Q1 II with? I usually listen to music using my iPod Touch 6 so I was thinking if I should get a portable DAC.
asierThis is my preferred DAP. My Sony 45. Though I recently got the Cowon Plenue J and sound-wise, its very comparable, but the Sony handles 256GB microSD chips better than the Cowon. Fiio Mont Blanc IEM amp.