What is your price range? Type of music listened to most often? Keep in mind it's not always efficiency of a speaker. It's how they work wiht said amp. That Pass amp is plenty powerful to rock some top good speakers. It's mostly class A if I recall right? It's also got a ton of current and that's more important that watt's.
I have a friend who owns Vandersteen Treo's CT and also owns your same amp with matching Pass amp and loves them together. He listens to a lot of rock and he listen's loudly. I ran my Treo's using an NAD integrated amp that isn't nearly as high current at your amp for a couple of weeks and the sound was pretty darn awesome. I didn't expect that as I have a large room.
I have a friend who owns Vandersteen Treo's CT and also owns your same amp with matching Pass amp and loves them together. He listens to a lot of rock and he listen's loudly. I ran my Treo's using an NAD integrated amp that isn't nearly as high current at your amp for a couple of weeks and the sound was pretty darn awesome. I didn't expect that as I have a large room.