Dear gentle reader please find my solution to the problem of getting a good, neutral sounding DAP; on the cheap.
 
My solution was typical for me; geeky and awkward; but I happen to think it sounds great!
 
So... My kit is...
 
Raspberry PI B (version 2?) - £35
IQaudio DAC+. £31  the latest specs seem to be :-
 

1. Full-HD audio – up to 24-bit/192kHz playback
2. Integrated hardware volume control (via ALSA), full 2v RMS
3. Built in High quality audio headphone amplifier (TI TPA6133A)
4. Class leading audio; 112db SNR, and -93db THD
5. Audiophile TI Burr Brown 32-bit/384kHz DAC (TI PCM5122)

 (http://www.iqaudio.co.uk/home/8-pi-dac-0712411999650.html) 
 
16GB class 10 sd card £5. This is for the operating system.
 
Battery pack, 10400mAH, Three usb power outputs; 2.1AMP, 1.2 Amp and 1.0 Amp - £20
 
250GB SSD harddisk and case £60 But you could stick a couple of usb sticks in 32GB stick cost £5 from ebuyer.
 
USB wifi card - £10
 
Lego to make a case. Free as I pillaged my sons...
 
So a total sum of parts is :-
 
With SSD hard disk £161, using usb sticks to give 96GB storage, £116
 
The operating system is Moode Audio :-  http://moodeaudio.org/ 
Moode audio is fantastic, you get complete control of the system, both the raspberry pi and the DAC. You can take control of the digital interpolation filter, choosing high attenuation with de-emphasis, FIR interpolation with de-emphasis, low latency IIR with de-emphasis and ringing-less low latency FIR. You can stream Itunes music to it. You can have a UPnP renderer and a DLNA server. It can play music back from network shares. The developer is currently very active and responds to problems quite rapidly and personally.
 
What you get is a great sounding system able to play pretty much whatever file you give it; including DSD files. It can up-sample your music too.
 
My default setting is to have it up-sample everything to 24bit/192Khz; this works with all my files (the majority of which are flacs) and only fails on 128DSD files; they stutter and distort; 64DSD files play without a problem.
 
The sound I would describe as transparent, open and precise; at least with my AKG K550s. I tried the Audeze EL8 open back at Richer Sounds and the system was able to drive them easily. I actually thought the sound had much the same open sounding, lean and clean signature as the AKG headphones, albeit with a lot more musicality and accuracy.
 
The player gives me the most important thing from a major upgrade; that of a 'new' music collection to enjoy.... This is not always a good thing... Poor quality recordings are now very hard to listen to. High bit-rate MPS or FLACS are a must. Modern recordings (maybe past ten years or so) quite often sound worse than older ones; due I believe to modern mixes tending to be bass heavy and compressed. Some recordings I though lo-fi have turned out to be real gems; I've a mp3 of a friends band; recorded live in their garden shed that sound great, I was listening to it walking home and I instinctively took my headphones off because it sounded like a band was playing outside my head...
 
I'll try and post a few more impressions when I can make notes on some specific songs. (May be a bit of a lag, just had baby number 3...)
 
But to summarise...
 
Its good enough for you to hear new things in recordings you know well.
Its good enough to show flaws in recordings.
Its transparent enough (and powerful enough) to handle a range of headphones.
 
 
All this in a package you can *just* cram into the largest pocket in a north-face jacket; and will happily scatter itself across the geography if you drop it.
 
I'd post a picture, but the system won't let me until I have more posts...
 


 

^
That "sounds" awesome! Your post has now given me inspiration to get a R-Pi and try this for myself. I even have a Wall-E Lego that could be a perfect housing for a desktop DAP solution.
 
I look forward to some pics once you've secured the rights to post them.