Happy New Year! I read pages 450 to 530. Thank you for your posts and sharing information. I'll summarize what I've learned.
- Dead n6ii might be resolved by holding the power button for 15 – 30 seconds. This fix is for Qualcomm protective mode.
- Dead n6ii on charger for 10 minutes might get warm. If so, it is NOT a Qualcomm protective mode problem. A slow charger (say, a USB 2.0 port on a laptop) for 30 minutes or so can cause the n6ii to start working again.
- Dead n6ii might be a loose cable or a bad screen. A blank screen but backlight at the edges can indicate the unit is ok, but the screen is bad. If so, the unit needs to be sent to Cayin for repair.
- A few on this forum have had problems with n6ii. But it seems to be a reliable design and build. (I've had my n6ii for about 18 months and have never had a problem.)
- Battery might be replaced relatively simply at a local phone service center. The replacement includes using heat and suction cup to remove the back panel. The battery can also be replaced by sending the n6ii to the place of purchase and/or the Cayin factory, but it can take several weeks to clear customs. (I leave mine on the charger when I'm not using it. Others prove a user should charge the battery to only 80%. The Accubattery third party app says I have a healthy battery. I won't try to speculate further.)
- Chinese firmware does not have Google Play and cannot be upgraded to the international firmware. This is an Android issue and not Cayin.
- n6ii and R01 can drive the Cayin C9 if the C9 is configured to "Pre" mode. (I use medium gain for the n6ii and low gain for the c9. This is easy and has been a game changer for me. Great sound! The detail, impact, and separation are increased without increasing the volume. A feeling of being in the room with the musicians is enhanced.)
- The n6ii and R01 should sound about the same as the Titanium version. At least, I did not read otherwise.
- Andy can't help us with predicting unannounced product. He is a nice guy, but he can't say
The front page of Head-Fi.com will say soon enough. Maybe Q1 or Q2, 2023?
- Wiring and grounding are beyond my ability to summarize. Thank you to each who have contributed. In short, I use my units as portable units and not desktops. I do not charge the battery and listen at the same time.
I know this hobby thrives on having the latest and greatest. The sp2000, M15, n8, n8ii, RS06, RS08 and others have great features and very good sound. I really liked the sp2000cu sound until I got my R01. The E02 wasn't to my taste for jazz, but it is great for other music. The n6ii and R01 sound (plus C9 amp when I am not mobile) are great for me. If I listened to other music, I might use a different motherboard. That said, I do not plan on using the A02 with the C9. The R01 is very good for me, and the C9 (pre-mode) lifts it further.
I hope my summary is accurate and my opinions not too far off. If clarifications or corrections are needed, please update the thread or PM me.