Can't say whether or not the amp by itself has an "airy top end". I have the amp hooked to a pair of JMLabs Diva Utopia Be's. Set up properly, I have not heard a system that can beat it for the same price. I can say that I have not heard any limitations in my amp/speaker combo, thereby no limitations in the amp, so far. At only 175W per channel, power hungry speakers might not fare as well, but you mention that you have efficient speakers so I doubt that will be a problem. What is the rest of your system?? I looked at Rotel, Krell, Linn and each time I came back to the Arcam. Just sounded more musical.
My advise is to try the amp in your system if possible. Won't know whether or not it sounds good with the rest of your equipment unless you do. See if the dealer will let you borrow it for a night or two.
My advise is to try the amp in your system if possible. Won't know whether or not it sounds good with the rest of your equipment unless you do. See if the dealer will let you borrow it for a night or two.