MANY receivers out there meet and/or exceed THX requirements, but aren't certified because it's expensive and just drives up the cost of the receivers. I used to own a Yamaha RX-V1600 which was THX certified, I know own a Yamaha RX-V1800, which isn't THX certified, and besides the lack of THX audio modes, the receiver sounds and performs the same to me. THX is more marketing hype than anything... I'm not saying a THX certification isn't good, it ensures you are getting a receiver that has enough power to drive speakers to a certain volume level for a given room size, but not having it isn't a big deal either.