Great review,love the photo´s with the cars

Great photos Justin, you really got talent!!! 
 
Unfortunately after testing A1 micro amp for the last few days, my experience about its sound improvement is not as enthusiastic as yours.  3rd bass boost setting is not even a bass boost, but rather an even signal attenuation (down) based on my measurements.  It's a really cute little portable amp, but I saw very little sound improvement benefits with my Galaxy Note 4 with and without A1 and using some of the most demanding headphones with higher impedance and lower sensitivity.  The only advantage is that i can push the volume to the max without hearing distortion like I would using HO of my smartphone.  For under $28 this will have a great benefit for those with older phones, I'm afraid.  Newer phones caught up with sound quality, and also A1 doesn't offer any benefits of significant signal level boost or soundstage improvement.  Again, my test is based around my Note 4, so I can't judge how it will pair up with other smartphones (the target for this little amp).

... and of course the benefit of hardware bass boost where Bass Boost 1 boosts sub-/mid-bass and lower mids, Bass Boost 2 keeps the same boost of Bass Boost 1 and lowers upper mids, and Bass Boost 3 just attenuates the signal down.

@twister6 
 
The main improvement will be with multi-driver IEMs if one has a source device with high output impedance that alters the frequency response too much. Plug the A1 between both and voilà, the source's output impedance doesn't matter anymore as FiiO's should be very low (like its predecessors) - I remember Westone included re-branded E6s with some of their IEMs few years ago.
Based on your description (of the third EQ setting), it acts similarly to E6's third setting, actually being a low gain instead of bass boost setting (e.g. if you connect).

@twister6 and @HiFiChris Thank you both for your posts.  I now have a better understanding of the 3rd setting, makes much more sense now.  

For me, I did notice a boost in clean power when I used my S4 with the Puro IEM500, though I am sure other devices will show different results.  I also enjoyed the 1st and 2nd Bass Boost settings with the IEM500, as it made them a little more playful and fun.

great review! I didn't even know they released this O.o

@m1ku - The FiiO A1 is not officially released yet.  Though it will be soon, though I do not have an exact date.

@HiFiChris : don't have any DAPs with high (or higher) output impedance.  This probably will work for Plenue and AUNE daps

Chris - do you have any details on OI?  I've asked Sunny - so awaiting reply.  They didn't list it in the specs.
 
And I'm with Alex on this one - I'll know further once I get it on test gear over the weekend (need an SPL meter to be sure), but at this stage the amplification stage at it's highest volume setting is not really adding a lot of volume.  There is some added volume - but it's not huge (I'd be surprised if its much more than 3-5 dB).
 
Would have to be a pretty weak source to be showing significant improvements.  So far tested with iPhone 5S, M3 and X1.  Sounds pretty good though - and the bass boost will be handy for those who want it (need to measure what that is doing as well).
 
Puzzling really. 

This would probably be a fantastic addition to the M3. Might have to buy the pair for the heck of it. If it's good, it wouldn't be a bad sticking stuff as a pair. Get more people started on the Hi-Fi hobby.. Lol

@sledgeharvy - M3 already sounds decent   But advantage of A1 hardware bass boost is solid!  Especially if you have some bright headphones, in Bass Boost 2 mode you are boosting lows and cutting highs - really a neat EQ preset!

@Brooko
 
No idea, Paul, as I don't have it. But assuming that they haven't changed much and the design is quite similar to E6's (because it seems A1 is its successor with about similar specs) and E5's and keeping in mind that FiiO never disappointed in terms of output impedance, I assume OI will be around/less than 1 Ohm, just like E6's (measured and calculated it a couple of years ago and it was ~ 1 Ohm).

Fantastic review, very well done!!

Hmm, I must admit, the thought of attaching this to the M3 is appealing...  I very well might have to pick up a new toy when it releases.

Well written review!
 
Is it the same output strength as the E6?
 
I agree in the description like a 'gateway drug' to buying more expensive Fiio products!  
 
I ordered it weeks ago, as I think the offer for the headphones and amp together for $69 is still active.  

If I find the minimum volume on my phone still too loud, would the A1 be able to lower the minimum volume? Thanks in advance.

I have an E06 for my portable amp. I'm using it to drive the JBL 04B cans I set inside my motorcycle helmet. A DIY alternative to the expensive Sena.

I've been using this for almost 4yrs now with no issues. Probably because I use it only when I'm riding, and when I'm not, it's safely sitting inside my helmet.

QUESTION: Would call it an upgrade if I replace the E06 with the A1?

Looking forward to your reply. Thanks in advance.

could you please help me. 
 
I would like to connect this to my tv because it has low and bad sound directly to headphones. 
 
but when I connect headphones to laptop or something sound is great. 
 
please help

Question: Can I charge fiio a1 on 5 Volts 2 Amp  charger? Thanks in advance