I'm currently using a Harman Kardon AVR75, which I've had since it was a new model. Now, I'm looking to upgrade to a newer unit, and I'm thinking about a 7.1 unit that can amplify a second zone (my outdoor patio). So... I've been looking around for the past couple of months and I'm really liking the H/K 635 (I'd maybe settle for a 435), a refurbed Denon 2805 or a refurbed 3805. I'd like to stay around $700 or so (and my wife would prefer $500). Any thoughts out there about what would both upgrade my listening experience and suit the purpose?