I recently acquired an AVT-8710 and just went to try it with a copy-protected tape, only to find the contrast blooming astronomically. No such problems with the unprotected retail tapes I've played through it.
I started with all of its internal proc amp controls reset, and then did brightness -1 and contrast -7 steps in an attempt to recover the levels. As you can see, this failed:
Attachment 22367
Without the TBC in the chain, everything is well within limits of the ATI 600's default settings (but the Macrovision causes the driver to garble the video every few seconds).
Attachment 22368
I started with all of its internal proc amp controls reset, and then did brightness -1 and contrast -7 steps in an attempt to recover the levels. As you can see, this failed:
Attachment 22367
Without the TBC in the chain, everything is well within limits of the ATI 600's default settings (but the Macrovision causes the driver to garble the video every few seconds).
Attachment 22368