Measuring the device you'd like @WolfX-700 to do?

[VMAT4]

Maybe for grins & giggles the S.M.S.L SA300:

 

[flowjm]

One of the Quad current dumping power amplifiers; the current Artera Stereo model, or the discontinued Elite QSP/909/707/606.

 

[Chrise36]

Topping l30 and a50s when available Spl phonitor x headphone amplifiers claiming better sound and power than thx amps at 5 times the price...atc power amps if you can get any and the usual "hi end" stuff krell jeff rowland musical fidelity bryston classe

 

[Robin L]

Fiio M3K

I repeat.
My points are as follows:

1. It's $70, I got a 512gb Micro SD for $80, I loaded it to the brim with Apple Lossless files. 2000 hours of music, easily accessible.
2. It functions as a USB DAC.
3. It has a recording function suitable for lectures.
4. It's tiny.
5. Used with low impedance IEMs and 'phones, it produces a beautiful sound, albeit at moderate or low playback levels.

If you're a basshead or want to go deaf, look elsewhere. But I have a number of situations where it's exactly what would work. With my Sennheiser HD 599 'phones, it's more than adequate for long walks with the open backs allowing for ambient sounds to still be audible. With my Klipsch X11i IEMs, more than enough power and quality at both frequency extremes. Via my AKG 167 "Tiesto" 'phones, there's clarity, bass [but not the impact or "slam" that more power would provide] and excellent top to bottom balance. For the price, it's a tiny miracle.

 

[50°F=Hellfire]

Measurements of the FiiO M15 would also be interesting. The manufacturer's provided specs suggest lackluster performance (barely more than 100 dB of SINAD, 3Ω output impedance), but so did those of the A5, and we all know how accurate those turned out to be.