Couple questions regarding the Sign Video PA-100:
Those that own this proc, have you noticed when using this amp that some vhs tapes will display a darkened area along the top of the video where many other tapes will display perfectly? And on those tapes that do have dark top, they DO NOT display this when the proc amp is not used. If so, any clues as to why? Just curious.

Also, has any owner messed with the internal jumpers and determined their use or function? Any difference?

The black level control of this proc is very nice and adds a great deal of quality to an otherwise so-so vhs capture. I like it a lot...!