Trying To Reassemble RAID6 Outside of NAS

Hey everyone. 

I have aa Asustor 5404T and I was recently upgrading from 4 1TB drives to 4 4TB.

I backed up my files before beginning but my backup got corrupted, which I only found out after removing the 1TB disks from NAS and deleting the volume.

Note I didn't delete the volume while the old disks were in the NAS, I removed them first so I believe the RAID set up and data should still be on the disks. Is that assumption correct?

I've used ddrescue to create images of the disks and tried to use mdadm to recreate the array from those images but no luck. I'm hoping I just missed something here.

I created the images and then added them as loop devices. First I tried using assemble for the device directly and then I tried using the partitions, still no joy. Here's my output for the mdadm --examine step: sudo mdadm --examine /dev/loop14/dev/loop14: MBR Magic : aa55Partition[0 - Pastebin.com

sudo mdadm --assemble --readonly --force /dev/md0 /dev/loop14 /dev/loop15 /dev/loop16 /dev/loop17

mdadm: Cannot assemble mbr metadata on /dev/loop14

mdadm: /dev/loop14 has no superblock - assembly aborted

sudo mdadm --assemble --readonly --force /dev/md0 /dev/loop14p4 /dev/loop15p4 /dev/loop16p4 /dev/loop17p4

mdadm: no recogniseable superblock on /dev/loop14p4

mdadm: /dev/loop14p4 has no superblock - assembly aborted