Ok, I've got to be missing something here. I picked up a DH-20A4H for a new build I did for a friend and figured I'd check it out, see if I wanted one for myself.
I popped a disk in it tonight and when I tried to run a disk quality scan on it, DiskSpeed popped up a box that says "Drive does not support this function".
I've tried multiple versions of CD-DVD / DiskSpeed including 22.214.171.124, 126.96.36.199, 188.8.131.52 and CodeKing's edited one for the iHAS series of drives.
The drive came with the QP5A "S" version software so I tried updating it to the QP5B "S" which didn't work either.
What am I missing here?
EDIT: It seems it'll scan CD's, just not DVD's single or dual layer.