Now seeing im presently using a/c cables that are in the $400 $500 $600+ range.Would it not make sense to go equally for a great 20 amp a/c cable for the the power filter?I agree with the others that it can make a difference, and that there is likely room for improvement. However, I would not by any means assume, as you appear to be doing, that a similar price = a similar level of performance in your (or any other) particular system. Or that higher price = better performance, for that matter.
See the comments by me and others in this thread, and this one, and this one, among others.
As was suggested above, you may want to consider using the "library service" of The Cable Company to try out a variety of power cords at various price points.
Good luck. Regards,
-- Al