After some days of usage, here are my first thoughts on the Shanling M6:
I love the form factor, it rests in my hand very well and the screen is bigger than my Hiby R6. The lack of soft key navigation is problematic for me as I am not a fan of the gesture navigation but I added some with an app now. It's not ideal because it doesn't resize the screen, it's just an overlay but it will do for now.
The 3.5mm and 2.5mm ports are great, they click and they feel very secure compared to the R6. I haven't used the 4.4mm so I can't comment on that.
Connectivity: that was my main reason to upgrade, my hiby R6 Wi-Fi is not good (I'm polite) and I can't stream Tidal on the move at work. I need to have it stay in one spot where the Wi-Fi is the strongest. Drives me nuts. So I am happy to report that the Shanling M6 is almost as good as my galaxy s10 Wi-Fi. It's very nice to walk around with the player and not worry about losing connection. For the Bluetooth, I have not used it extensively yet so I can't comment on it but my UE Booms and Megabooms seemed to like the M6 just fine. Need to test with my wireless iems.
Sound: I love the sound of my R6 in balanced mode and I love the sound of the M6 in balanced mode. They sound fairly similar but maybe the M6 has more details in the mids and treble. The bass is either a wash or the R6 has a smidge more.
Overall the M6 is a very impressive device and I am happy with the purchase. I wish the device would come with screen protector already applied and a basic case in the box... But those are minor details.
Shanling, update the M6 to Android 9 64bit, add the navigation bar to your Android build (and release the kernel source?) and then you will have the perfect $500 DAP.