I listened to the Leben amp driving a pair of DeVore Nines. It was in a really cool shop in Montreal, and the front end was a high end Clearaudio table with a Benz pick-up. The music sounded absolutely wonderful, and the shop owners were really happy with the synergy between Leben and DeVore. I don't know how Leben matches up with ProAc and Harbeth, but I do know that I loved what I heard. Good Luck with your speaker search, and have fun ! It's all about the music, so enjoy whatever sounds good to you.