I'm building a floating sub-floor for my home theater:

Which works best as a transmitter of low bass frequencies? (I'm looking for that "tactical feeling")

On a side note - seems that OSB would be easier to work with as it has less curl to deal with during installation.

This may be useful:

http://www.ownerbuildersolutions.com/PDFs/FHB_wtd_plywood.pdf

It says OSB is ~10% heavier, but has the same strength and stiffness. Doesn't go directly to your question, but indicates they are pretty close.

After considerable research - OSB it is (at half the cost).

Now what would be better to use underneath? Rubber isolation pads (cut into 2" squares) - or an acoustic floor mat (ie: Owens Corning).

Now what would be better to use underneath? Rubber isolation pads (cut into 2" squares) - or an acoustic floor mat (ie: Owens Corning).

Are either available at the usual big box stores or are both a specialty purchase?