I have had the opportunity to listen to both the Ayre and Cary (I own the Cary). As with everything in this whacky hobby it really comes down to personal preference. I do not think the Ayre and Cary sound similar at all. I listened to an all Ayre setup (K1xe + V1xe) with BW 802d speakers. The sound was great! Very holographic, easy, airy. Everything sounded BIG to me. For my taste, it was a bit too BIG and a little lean. Some people would love the detail of the Ayre. I happen to prefer a slightly dark and warm sound with an empahsis on the midrange, which is exactly the Cary house sound. The 306 is just so smooth. The bass is incredible. Do I get the impression that the Cary has as much detail and resolution as the Ayre? No. But that is not to say that the Cary does not have detail and resolution it is just that the character of the Cary presents the music differently. The first impression I get from the Cary is its great midrange and bass. For example, last night I actually got chills listening to the Cary. I could not believe how magical the vocals sounded, so real, so intimate. Again, this suits my listening preferences.
So the bottom line is that both players are great! What sound are you going after? That will dictate which player is right for you.