Building a listening room from scratch

Wow! That sounds pretty neat. Although in the end, you might ease-up on the extensive sound absorption lest the room be too acoustically dead.
Rick

If possible lay some large tile on the floor lest your bass get soaked up by the wood and space below. You ARE going to insulate the walls with something other than burlap right? Otherwise, going to have a monster heating bill.
What about 20 amp service (multiple) for your monoblock amps and power conditioner(s)?

Cool. I am a big fan of using rock wool insulation. I used rock wool in the ceiling and interior walls and 6” regular fiberglass insulation in the exterior walls of my basement listening room. I used sheetrock but floated the ceiling sheets on aluminum brackets to reduce transfer of sound to rooms above. The room has a concrete floor poored over tons of crushed rock, so quite different than a wood floor.

The room is pretty neutral with only a few nodes in the bass region. With a bookshelf running the full length of one side wall and only three smallish windows on the back wall, the room has almost no reflections and treble is a tad reticent below about 50 Decibles. Above that volume, sound is outstanding, with only the reverb of the original recording space presented as well as the speakers can.

I would try setting up your gear with nothing covering the insulation and trying it, and then try tacking up at least half of the space with dry wall, see what sounds better and go all in with that.  Agreeing with Sisyphus51, I am wondering if you really want to approach a full “anechoic” listening space. Also, are there any health issues associated with exposure to unsealed rock wool? Finally, I find having a hard floor with “dead” walls is a good combination, try the tiles suggested above as well.

kn

Dweller, there is 14.5” of rock wool BEHIND the burlap, as described above. The house is being renovated to perform to a high energy standard. On the HERS scale of 0 to 150, with 150 being old existing homes, 100 being new homes, 70 being energy star, this will be a 40. That should cut my energy bill by 75%. The floor is 150 year old wood, we want to enjoy the beauty of it, and save money, so no tile. I will have 20 amp shielded service: how did you know I have a pair of monoblocks? NY Audiolab Julius Futterman OTL 3s, converted to triode and modified with audio grade caps by Jon Specter (Al Cooper’s cousin). 

Knownothing, rock wool is considered to be safe environmentally.