Once you used the Adaptec-Card, it has surely written it's DCB (even it was JBOD) on all disks ... normally first 4k on each disk. Then you made the Superblock (so called DCB by mdadm) on top - and after that magic failing upgrade you change the controllercard ...
Is it possible that the Adaptec changed disk geometry (possibly hiding sectors from the beginning of the disk since used 'internally')? Just asking since I'm currently fighting against a stupid USB-to-SATA bridge which does the same but from the disk's end (so it doesn't hurt that much, only backup GPT corrupted)?
@calvin940 in case your syslogs date back from before the controller change it might help to provide output from