As excited as I am for this too, don't presume that this will necessarily be a substantial upgrade from the Valhalla and the 650/600, or any other combo you have enjoyed currently or in the past. Sometimes certain combos have a special synergy (I haven't heard the Valhalla so can't comment on potential synergy there). And there is also the role of personal sound signature preferences and the specific type of music you listen to and how that intersects with the specifics of an amp/headphone pairing.
The Valhalla and HD 650 exhibit fabulous synergy IMHO. That doesn't mean I'm not excited about the Liquid Platinum, though - there are always new synergies to be found!