Hi buddy,
 
I usually agree with your reviews, unfortunately I think we have totally different views on the AP60. There are some flaws that you haven't mentioned (probably you haven't detected them?), along with the promised features that haven't been activated yet

Please don't take my post as a personal attack because it isn't meant as such, and I know that different people have a different view on things sometimes, but aspects like the not yet activated USB DAC out, permanent moderate bass roll-off regardless of load impedance, the hiss that would be okay for a very powerful player but not for one with a weak and supposedly IEM-friendly output and that the touch button control is not the most accurate (on the go) are things that don't let me see the player achieving more than 2.5 to 3 stars (the latter if the DAC output was finally activated). Maybe I should already upload my review as opposing point of view today although I thought I would hold it back until the USB output was enabled.
 
Cheers,
Chris

Hi Chris, glad you shares your view point. I dont take personal offense, and I do like feedback. What firmware version are you on? I am on 0.05B, which yielded many improvements. But as far as hiss and roll off go, I'm sorry, I legitametly couldn't hear it. What IEMs did you test the AP60 with? If I have some of the same ones, maybe I could do a test to try and corroborate your findings?

I didnt know that USB DAC was even a feature. However I do stand by my rating, as I would personally buy this if I needed a new DAP.

I'm on the same firmware. What I really like about it are the scanning speed, design, functionality, responsiveness and that it takes exFAT formatted cards without any problems.
 
If you are listening to music that extends clearly below 100 Hz with IEMs you are really familiar with, you could probably notice the roll-off towards the sub-bass. (I've measured it here after I noticed that my IEMs have got less sub-bass than I'm used to : http://www.head-fi.org/t/800208/#post_12937149)

For testing, I used the Sennheiser IE 800 (just very faint hissing), Ostry KC06A (rather strong hissing), Shure SE846 (rather strong hissing), Ultimate Ears Triple.Fi 10 (audible but not as strong as with the Ostry/Shure), Etymotic ER-4S (silence) and Pai Audio MR3 (rather strong hissing).
So yeah, sensitive in-ears except for the IE 800 and ER-4S. As an explanation though, not everybody is equally sensitive to hiss. I also wouldn't be complaining as much with a DAP that has a more powerful headphone output, but the AP60's is not strong and for its power output, the noise floor should be lower (imho).

USB DAC in- and output were announced features. The DAC input is now working perfectly (since 0.05) and I hope that the output will be enabled soon, too.

Thanks for the review! I'm very interested in this DAP and may order one. How do you find the button layout? Is it too small an area? Do you get very many accidental clicks?

@HiFiChris I don't have any of those IEMs, but I've tested a couple of the ones I currently have with me: RHA T20 (Minor hiss), C&M 01'16 (Moderate hiss), C&M 8'13 (Minor hiss), Thinksound MS02 (No hiss). It seems that, based on the trend you are hearing, your upper-register of hearing is better than mine. I'll have to update my review to reflect my personal findings, thanks for checking me. No matter what I tried, I couldn't hear the bass roll-off. Sorry man. Perhaps the built in EQ may be of use?
 
@bruce1967 The button layout was a little weird at first, coming from the AP100. However, after two or so days I stopped making accidental presses. Now, ever since I was stuck with a Nokia Lumia 900 for three years I'm not a fan of capacative buttons, but I made an exception for this DAP because I liked the UI. The area is quite small, it just requires time to adjust to.

@HiFiChris Maybe the issue can be rectified via a firmware update? Did you alert Hidizs yet? They are on Head-Fi if I recall correctly. 

@Cinder
 
I'm just over-cautious with my hearing but there are other members who are just as sensitive. The IEMs you have are also of lower sensitivity than typical multi-driver and the most sensitive single driver IEMs, so this is also one thing to consider.
 
The EQ doesn't affect the very lowest bass.
 
I've informed Hidizs in the dedicated thread and shared my impressions in that thread several times. I think it could be corrected with a software update (if they apply a negative EQ curve to the roll-off) but it is mainly a hardware-related issue. Some players in the $10 and 20 range also have a roll-off in the lows, and I really expected the AP60 to be ruler-flat as it really is no sorcery and players like the ones from SanDisk or AGPTek also measure and sound linear despite their price.

Imvho, the AP60 works better as a pure digital transport device for Bluetooth and external DACs (as soon the output is enabled).

@HiFiChris
 
Oh yes, I don't doubt it. I don't mean to come off as skeptical, I know for a fact that I am the inheritor of some shoddy hearing, especially in the much higher register, so I think I'll have to update my disclosure to include this information. 
 
But I do think that your expectations are reasonable given the cost of this DAP. I think our disparity in ratings is likely due a difference in how we perceive the value of a DAP, and the weight we place on each category.
 
I don't really own too many sensititve IEMs, and the ones I do have that are more sensitive than these are currently an hour drive away. I'll try to make my way down to them and test the AP60 on em.