I just received my QP1R and I will say this:
QP1R is a very nice DAP from a build and looks perspective. It is solid and the UI (I have v 1.0.4) is really quite good and responsive. The track wheel is a little stiff, more so due to the fine finish on it. I lick my index finger slightly and get good response. I may put a light dual sided tape on it temporarily until it loosens up a bit, but definitely not a deal breaker. You have 2 custom EQ settings you can set up or just run w/o EQ. I prefer playing with the settings as they do add some nice SQ depending on the track.
As for the main point....SQ. I must say this is one truly nice unit with superb imaging and this is with only about 5 hrs listening on my Fostex TH-xxx and Dharma 1000 headphones (both easy to drive and sound fabulous on this DAP. I can't wait to try my HD800/700/650, AKG K812, Audeze LCD-X/XC and a few others. The sound is so rich that it is really hard to believe you can get SQ and resolution this good from a portable device. It definitely has enough power for headphones up to 300 ohms and be able to drive them beyond what is bearable to the ears in high gain mode. You also have medium and low for low impedance phones and IEMs.
How does it compare to the competition???
Cowon Plenue P1 (I have it). The Cowon was my favorite DAP until I bought the Luxury & Precision L5 pro and now the QP1R.
The Cowon is very nice and has a very nice UI and the sound is truly excellent, especially with Jet Effect 7 (built in with the EQ functionality). Definitely not a DAP to pass by. I have had it for 6 months and I have not had a problem yet and it has quite a bit of power.
Not quite as much as the QP1R or the L&P L5pro much less the Acoustic Research AR-M2 which is a beast when it comes to power and also has terrific sound quality and resolution. It will power anything you throw at it.
Now:
QP1R vs Cowon Plenue P1: Tough choice but since they essentially in the same price range in the US, the QP1R is the better sounding and better looking DAP IMHO. The Cowon UI is a little nicer but it only has 1 SD card slot up to 128gb and 64gb internal which is technically enough. The QP1R just has such a clean and neutral presentation with a better and faster overall sonic attack in the MID and Treble region. The Cowon presents more low end bass, but the QP1R using the EQ gets quite nice without being too bass heavy and "Boomy sounding". I personally look for SQ and resolution along with a nice all around sound stage which it does very nicely, but a lot depends on the headphones as well. So, if I had to choose just one, it would be the QP1R w/o any hesitation.
QP1R vs L&P L5pro: This is a tougher one to choose. Both are really fabulous. Both have exceptioanl SQ and overall resolution and imaging. The L5pro a little more on the warm side but not by much so it is nice to have both units. UI is more developed on the QP1R. L5pro has a few more bugs to iron out and needs an adjustable EQ. Right now it only has preset options (rock, jazz, classical, etc). I use rock as I find it suits a wider array of genre. also a nicely built and solid DAP but it is NOT the QP1R. The Questyle takes this category against all comers in my opinion, even goes straight head to head with the Astel & Kern players. So, in my opinion the winner overall is the QP1R.
QP1R vs AK120II: Well both have great build and looks but in the overall SQ and imaging department, the QP1R is the clear winner at just a little over half the price of the AK. So the only category that the AK wins is having balanced 2.5mm (kind of goofy since all other players use 3.5mm). But apart from that, it really is no competition. Throw in the money factor and value, The QP1R blows it out of the water in my opinion.
QP1R vs AR-M2: another tough one. Here it really depends on what you want to use it for. They both sound really great but overall imaging and clarity goes to the QP1R. If you plan to drive harder to drive full size headphones and primary usage will be full size cans, I would "ever-so-slightly" lean to the AR-M2. The AR-M2 does not have high/low gain settings. It is a power house DAP that sounds great. If you plan to use IEMs primarily, the QP1R is the clear winner here. If you plan to use both full size up to 300 ohms and IEMs, the QP1R is still the SQ and resolution winner IMHO. It is the better sounding unit overall. Both are built like a tank and the fit and finish are truly wonderful on both units. The AR-M2 is larger in all dimensions and "heavier". It is a really serious DAP for full size cans. Again, glad to own both as my preference is full size cans. But as an overall winner, I would slightly lean towards the QP1R again.....not by much but it is a cleaner sounding DAP. The UI on the AR-M2 is Android based (a toned down and simpler Android) but it is quick responding and you can swipe the screen like a typical smart phone for usage. AR-M2 does do better here if that is your thing. To me sonic performance is the main driver by far for any DAP I look at purchasing. So these 2 units are the 2 best overall with the edge going to the QP1R and at $300 USD less than the AR-M2.
More to follow once I get to break in the Questyle and use it with more headphones as well as IEMs. Thanks and all the best!
P.S. You will not go wrong with the QP1R by any means and it is better than the Cowon Plenue P1 to give a final answer to that question!