Not your everyday bookshelf speaker?

I am looking for a bookshelf speaker. I currently have some B & W CM5's, which I like a lot, but I feel that my little Sonos 55 watt amp is underwhelming while driving them. I am looking for suggestions about speaker companies that are seldom heard of that make high value, highly efficient, excellent sounding speakers. Kind of like finding the proverbial needle in the haystack - hidden treasure speaker company. Any suggestions? Model numbers?
Thanks..