Somebody wonders O2's sound quality?
It just awesome.
You can hear and look linnnnnner outputs and just no hiss with no clippings
Driving? Earbuds, Er4s to K701,T1,HD800
Planner magnets, Dynamic, Balanced Armature Drivers
16 Ohms to 600 Ohms, low efficiency to high efficiency, no matter
My O2 has custom Gain x1, x2 so Definitely No clipping in any conditions also lower noise
(Default x2.5 x6.5. x6.5 makes some clips with high volume @ battery only)
Even Default setting you can not hear anything form O2 amps
If you can use AP's or D-scope, or RMAA You can actually see them
O2 shows clar sound, not like tube amps
Just pure Amplifying at all
No more Harmonics, Hiss, Distortions, Buzzing
Pros
Definitely highest grade Audio quality
Pure Amplify
Infinite number of volume levels
Low output impedance(will not change Frequency Response of your IEM to Full sized Headphones like Er4-S, K701, HD600, T1 ,HD800, etc)
Good design (to me)
Selectable Gain
Cons
No battery level indicator
Volume unbalance with low volume(cuzed by Character of Analog volume, just use upper than 9 o'clock, recommend over 12)
Too engineering nerd style design (to somebody)
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Amps are not for make dramatic sound(Cables too)
Amp helps source devices with high input impedance, that keeps low frequencys with poor amped portable devices or DAC works better
If you use apple devices like iPod touch 5, iPhone 6 you don't need it at all(for sound quality, but it can be helpful to mental effects, so You may Feel better with out actually no sound changes)
P.S. Somebody have measurements of iPod touch 6 tell me! (FR, output impedance, etc)
↘️Mine with iFixit form Massdrop