AP80 Pro is packed with a lot of wired and wireless options I would like to go over below based on what I have tested.
USB digital out.
I had no problem using it as a transport driving various USB DAC/amps where the connection was flawless with devices being recognized right away, including Hidizs own S8. Interestingly enough, despite S8 using CS43131 DAC, its 3.5mm output sounds very close in tonality and soundstage expansion to 2.5mm BAL output of AP80 Pro. Maybe just a little bit brighter in upper mids/lower treble, but it is very close. And based on that, S8 makes a better add-on for AP80 which can bring its performance closer to BAL output of AP80 Pro.
As a side note, S8 is a nice little DAC/amp with a dedicated Volume +/- controls and compatibility with Android, Windows, iOS, and MAC devices. It is not very powerful, better for use with IEMs, but its revealing tonality and wider soundstage expansion can enhance and improve the sound of either your phone or your laptop.
To enable the LO from 3.5mm headphone output, you have to select it in settings. It sets the volume output to fixed max level. I tested it with E12A, and found no clipping or distortion.
Connected to my Thinkpad T480s (Win10), I didn’t have to install any drivers, just selected USB Audio in AP80 Pro settings to enable DAC. Windows recognized the device, installed necessary files automatically, and was correctly displaying bit rate during the playback.
I tested Bluetooth Tx with various wireless headphones and IEMs, and found the connection to be stable and operation in open space 35-50ft away (depending on which headphone/earphone I was using). Also, Bluetooth Rx works fine, turning AP80 Pro into a wireless dongle connected to different IEMs.
The conclusion of my original AP80 review is still valid when looking at AP80 Pro. AP80 Pro is a great mini-DAP which took the “cool factor” of M0 micro-DAP one step further by making it more functional and user friendly thanks to a bigger 2.45” display size and physical playback buttons. Adding on top of that bi-directional hi-res Bluetooth which allows nearly lossless wireless headphone pair up or turning the DAP into a wireless dongle, USB DAC functionality, USB digital out to use the DAP as a transport, and a good sound performance – and you got one cool little DAP!
But I think many might have a question if they should upgrade from AP80 to Pro or not. First of all, if you are looking at either AP80 or AP80 Pro, for only $30 more Pro version makes more sense due to the improvement of balanced output performance (wider soundstage, blacker background) and support and enhancement of up to DSD256 native playback. But at the same time, if you don’t care about DSD256 and happy with performance of AP80 and its pair up with your favorite IEMs, I don’t think there is a necessity for an upgrade. I know that people are looking into AP80/Pro because of its “small” size and “big” functionality. And both AP80 and AP80 Pro nailed it!