I've never heard the Clayton but am interested. For reader's info: At '07 T.H.E. Show in the ModWright inner room they had the latest greatest balanced preamp circa $4500, circa $12k Belles Power Modules huge class-a amp & $21k/pair Escalante Design monitors.
Someone in the industry w/ no known direct connection w/ Clayton, whose opinions generally matched mine on equipment w/ which we are both familiar, said the little $4k Clayton SM40 beats the big ole Belles heard in that room that day. That got my attention.
My current amp short list includes the Clayton, Ayre V-5xe & $4500 Primare A32 (A32 sounded fantastic driving $11k/pair Martin Logan; speakers current model as of early '07, audibly improved vs. earlier).