I have two 10 year old Lexicon amps in a home theater room. I'm replacing the 10 year old pre/pro with a new Integra DHC 80.1. Should I replace two Lexicon NT 512 amps that are in the system? I read that these were made by Bryston which gives a 20 year warranty on their own brand, but Lexicon only gives 5 years on this private label version. I wonder if they are worth sticking with.