The Adiago's might be a better fit for you becasue they're front ported. I had mine about 30" out from the back wall and they were amazing. From what I've read, the Harbeth's need a lot of space between them and the back wall.
Acoustic Zen Adiago vs. ATC SCM40
Any thoughts on these speakers? Neither are sold in my town and I am desperate for input. Adiago are glowing reviewed everywhere and the ATC are well regarded as well. I have a smallish listening room (12x15) with tube pre-amp/amp. Listen to all kinds of music. Also considering the Harbeth SHL5 but they considerably more money and they would have to be twice as good to buy.