It looks like it will be a wonderful place, JC. Good to hear that the Sonopan will not be exposed. Otherwise it could double as a second anechoic chamber for Ian \:\) . It may be too late now but it would have been a good idea to have staggered stud walls to decouple acoustic surfaces.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated