First, what's your budget?
Second, what are you looking to drive? IEMs? Full size headphones?
Third, do you absolutely need to have 2x microSD (TF) card slots?
Fourth, do you plan to use an external amp? If so, by line out or by USB?
If you're looking for something around 300 Euro, then I'd recommend the iBasso DX120. 2x microSD (TF) cards, line out, USB DAC, and a pretty good sound quality that should meet/exceed what you've got out of the FiiO. Plus, you should be able to use the line out function for an amp if you already have the FiiO A5.
If you're willing to spend more and want to have a bit more power as well as the ability to discover streaming/bluetooth, the Astell&Kern KANN is still a powerful portable device that produces good sound and battery life, plus can drive many full size headphones without the need for an amp.
I hope that's helpful!