First of all I'd like to introduce myself:
I'm 29 years old, working in a high-end Hi-Fi store for some time now and therefore I consider myself being somewhat capable of reviewing this type of equipment honestly and as subjective as possible.
I have gone through a wide variety of DAC's/amps both portable and stationary and spent pretty much a month deciding what device to finally spend my money on, and it hasn't been easy.
My opinions are nonetheless my personal opinions and you might not agree, and at the end of the day you should always trust your own ears and personal taste when it comes to audio.
My first candidate was the Denon DA-10 and my opinons on that device is:
More output power and higher input bit depth and sample rate is supported although to bulky for me personally. Also it had some problems with balance when it came to the volume knob.
My second candidate was Oppo HA-2:
It is indeed a better device than BeyerDynamic A 200 P, but its also pricey and somewhat more bulky too.
I also tried out a bunch of other devices such as (among others) Denon DA-300(stationary, fantastic), NAD D1050(stationary and absolutely amazing favorite stationary <300 dollar dac/amp), Cambridge DacMagic Plus (Stationary and great although a bit too analytic and focused on midrange/treble)
Back to BeyerDynamic A 200 P:
It had some problems with my Samsung Galaxy Note 4 when it came to native playback trough USB from sources like tidal, youtube etc but it's possible to use it nonetheless.
Supplied cables worked great with iPhone as well as Samsung.
Form factor is unparalleled.
Audio character a bit an the bright/hard side for me (and my headphones, but that's a matter of personal taste and headphone audio character).
European volume limiter is easily overridden (thank god, it actually had a lower output volume than my phone as default).
Distorsion might be somewhat noticeable at higher volumes.
Volume is decent but nothing special for this kind of product.
It would benefit from an analog input.
Native 24 bit/192kHz support would have been perfect.
The reason I chose this product though is because:
Form factor, design
It's still an amazing addition to your smartphone audio wise.
Good battery life.
DAC provides a good soundstage.
The leather pouch is actually a nice bonus.
And the price is good for a premium product (which I do consider this being)