Great review! I'm interested in picking one up to complement my X1 as well!

Two quick comments from a fellow Q1 owner:
 
1. Spotify works just fine for me coming out of an Asus ZenPad Android tablet with a generic Android OTG adapter
 
2. Q1 also works just fine plugged directly into a USB port on my Samsung chromebook (a pretty old one, at that). Again, Spotify works like a charm.

great review, owing the Q1 myself as well as the X1, the short flat 3.5mm line cable is absolute genius! 

great review focused on usabilty as well as sq....kudos!!!

As an amp, it works fine. It can push full sized cans 300-600 ohms, to the point where you can hear the sound several meters away from your face without introducing too much noise or distortion. The physical profile is also fairly small compared to most Amp/DAC out there.
 
As a DAC, I suppose it can read up to 24bit/96khz and has OTG support.
 
Apart from that, I can't say there's much to say about them. Sound is mediocre, plenty of on-board sound (computers and phones) are better though not neccessarily cheaper. Can be a bit harsh sounding. I think you'd be better off saving up for a more capable phone/DAP. They are relatively cheap though.

Hi VVC, I am also a WindowsPhone user (1520) and hunting for an affordable DAC/AMP. Have you tried asking MS if W10M and a Firmware update specific to L1520 be able to enable OTG LO?

Nice review.  I have 2 of these and for me they are obvious improvements to my Note II, my on-board PC and my X3 2G (unfortunately) with my many headphones.  My Note II works the Q1 with OTG cable and Spotify (my X3 2G does not, unfortunately again).  My most recent Q1 has a looser volume pot, but still sounds great, love them both.  Got a Fiio E10K on the way!!!

@NewbieForever Welcome my fellow WP user. As far as I can discern (I am a tester for WP10), The OTG audio requires new hardware in edition to the software. Meaning the 1520 will not work. If I can find the source that showed this I will PM you.

@cjs001, I completely disagree with your experience with the Q1's DAC. To me it sounds better than the DAC on the X1 amplified with the Q1.
I'm not quite sure what genre of music you listen to, but I don't find it harsh at all, it's actually quite "easy" to listen to, and I find it airy. I like the DAC on the Q1 quite a lot and use it at work all day on my work laptop.
Good job on the review Vividcard. Nice dog.

@ShampooCA Can't say I've heard the X1 so maybe the Q1 does sound better, but I have been listening to a lot of other sources ie. iBasso Bushmaster, DX80, Govibe Porta-tube, Lotoo Paw Gold, Sony NW-ZX100, Sony NW-ZX2, Xperia Z5, PCM-D100 and the Meridian Explorer just to name a few and compared to all the above, I stand by what I said earlier. They are however pretty good value gear given their pricing is significantly less than most of the stuff I've mentioned especially if you wanted a really powerful and cheap amp/dac with OTG capabilities.
 
I do however notice the sound does take an airier quality when you have the bass boost toggled on. So perhaps it is an improvement to the X1 which doesn't inspire confidence, but that could also be a matter of personal preferences.