Sound Devices MX-LMount

I started using it and will share some initial observations.

First, the negative – power supply:
4 x AA batteries are definitely not a viable option for powering the Sound Devices MixPre-6 II!

With a fresh set of 4 x AA batteries, I was able to update the firmware to the latest version (in my case, MixPre_9.02), and after the update, the brand-new batteries were already drained!

I then replaced them with another set of fresh batteries from the pack, and I could maybe record for about a minute using two phantom-powered microphones before the battery indicator dropped rapidly, and the device started complaining that fresh batteries were needed!!

After reading other users' comments, I initially couldn't believe it was this bad, but I ended up ordering the following on the same day:

Sound Devices MX-LMount
2x SupraCell Sony NP-F970 batteries
A dual charger for these (SONY NP-F970 Dual)
Since I plan to do field recordings where no 220V power supply is available, I need a reliable power source that lasts at least 3 hours!

On the positive side:
The sound quality is superb!