The Manleys will drive pretty much anything. I run Thiel CS2.4 speakers which are 4 Ohms and significantly less sensitive than the Focus HD. The Thiels NEED a good amount of power to come alive and that they do with the 250wpc Manleys - or 100wpc in Triode mode.
I recently retubed mine with the more robust 6CA7 tubes. 10 6CA7 per monoblock. Ouch!