So I was at a store shopping for a new smartphone and mentioned that I'd want it to have great sound so I can use it with a FiiO amp and listen to music, without a need for a dedicated DAP. The shop assistant quickly identified himself as an audiophile and said I needed an HTC One, and with that, he claimed, I wouldn't need a portable amp for most portable headphones, since its on-board amp is so good.
Is HTC One really all that?
Luckily I bought a used HTC One M8 a few months back.
To drive my 32-Ohm Soundmagic HP200 to a decent volume (for my ears), the HTC needs to have the volume set to around 75%
To drive my 250-Ohm Beyer T90 to a decent volume, need to run volume setting to around 85%-90%.
Guess the HTC ONEs headphone jack amp is roughly about equal to a $24 FiiO E6 headphone amplifier.
I'm finding my HTC ONE to make a very decent music player.
I normally listen to music (256K mp3) on my PC, using Foobar2000 (w/WASAPI) and a ($300) Audio-GD NFB-15 external DAC/amp.
Lots of used HTC ONE M8 for sale on eBay.
Should be able to find one in decent/fair shape for around $150
You might(?) be able to improve the audio on the HTC ONE if you install a third party firmware, something like Cyanogenmod.
Or maybe just a third party music player
http://www.androidcentral.com/best-music-players-android#slide3