currently out of 13 cards tested only 2 have sustained writes from front to back without errors at mixpre6 (v1) maximum bitrate of 4.5 MB/sec
I hope SD takes this issue seriously or its gonna be a lot of bad press when mixpre6-II and 10-IIs bump up their bitrate with 32 bit
currently the only card they can endorse gives 80 minutes at max channels/bitrate on a mixpre-6 II and 55 minutes on a mixpre-10 II.
Though in general I have had an easier time with Zoom recorders on powering and card use than with the SD633, the manual for the upcoming Zoom F6 (also 6 ISO tracks plus L/R mix) notes:
192 kHz cannot be selected when the recording mode is Float (32bit) and the LR track is on.
When 192 kHz is selected, Dual (16+32bit) and Dual (24+32bit) cannot be set.
And the F8n also has the following:
When 192 kHz is selected, L/R tracks will not be recorded. The Input Delay and Output Delay are also disabled. Moreover, Auto Mix, Ambisonic Mode, and Input Limiter > On/Off > On (Advanced) cannot be set.
So maybe Sound Devices has to convert this from a bug to a feature.
I am currently testing my MixPre-6 II at 32 bit float, 6 tracks + L/R at 96kHz, which is all I will ever use.
Jeff