In my nearly 40 year in cable I've never heard of a "tuning adapter"
Are you speaking of a catv converter/ set-top box?
If you've already had a technician come out and troubleshoot the problem why didn't you let them fox it while they were there?
If the line is bad an amp isn't going to help you all you would be doing is pumping more signal into a bad line.
If you want to drop 2 to 6 grand on a signal meter just look in the classified section of this site. But gaging from your questions you most likely wouldn't know how to use it.
Save your money and let Cox fix your problem.
