Meizu HiFi Audio Pro = Earbuds Heaven
Here is my
Meizu HiFi DAC Headphone Amplifier PRO aka Meizu HiFi Audio Pro driving a pair of Thai custom-made earbuds,
Crystalcore Audio Kryptonite (150Ω); 2.5TRRS Balanced via a handy little
ddHiFi DD DJ35A Balanced Adapter. I use this lil' dongle primarily as a USB DAC/AMP at my desktop and use it with my smartphone when travelling but most always when in "flight mode". Please kindly note that this dongle is well-documented to exhibit unfavorable EMI interference when used closely with certain devices (e.g. "active" 3G smartphones). I have not personally had an issue yet with any device but the problem does exist so I think it best to warn others about it. This is really the only drawback I can think of in regards to this well designed device.
I have been very impressed with this little dongle; so powerful, clear as a whistle, and in such a small form factor. It simply reeks of Wolfson and in a very good way!
Meizu HiFi Audio Pro (Model CP19P) uses Cirrus Logic's flagship CS43131 DAC chip (32bit/384KHz audio) coupled with two Texas Instrument's OPA1622 second-level op-amps... again, very reminiscent of Wolfson design approach and implementation. Listed by Meizu as having up to ~1.75Vrms output (as determined by auto-impedance detection) with a thrust of 30mW @ 32Ω (6.7mW @ 600Ω) it
has been measured to be much, much higher @ 87mW @ 33Ω (
https://www.audiosciencereview.com/...hifi-pro-usb-c-phone-dongle-dac-review.10423/ ) and if "tricked", via a headphone adapter and/or audio extension cable, will output at ~2Vrms with a thrust of 100mW @ 32Ω (13mW @ 300Ω); <0.0002% THD+N @ 1kHz; >123dBA (as tested and documented here:
https://zhuanlan.zhihu.com/p/94991395).
Headphone Adapter (Audio Extension Cable) Trick:
1. Firstly, before plugging the Meizu HiFi Audio Pro into the source (phone/pc), plug an empty adapter or short audio extension cable into the headphone output jack of the Meizu HiFi Audio Pro.
2. Secondly, plug the Meizu HiFi Audio Pro into the source (phone/pc) via it's USB Type-C plug.
At this point the device "sees" the empty adapter as ∞ (infinity) impedance and therefore "activates" the high-gain/high-impedance mode.
3. Thirdly, plug earphones/headphones into the adapter already plugged into the Meizu HiFi Audio Pro.
The device will remain in the high-gain/high impedance mode no matter the impedance value of the earphones/headphones plugged in
To turn off the high-gain/high-impedance mode, simply unplug the Meizu HiFi Audio Pro from the source (phone/pc); remove the adapter; plug the Meizu HiFi Audio Pro back into the source (phone/pc); plug earphones/headphones directly into the Meizu HiFi Audio Pro which will then recognize the plugged in earphones/headphones impedance value via it's normal auto-impedance detection system as accordingly.
A window into the guts of this mighty dongle. An excellent teardown can be found
here.