Wayne Parham Messages: 18825 Registered: January 2001
Illuminati (33rd Degree)
If you will put the speakers in place in your home and rarely move them, I would prefer MDF.
On the other hand, if you plan to move the speakers regularly or expose them to a high-humidity environment, then go with Baltic Birch.
MDF is a little better acoustically, but Baltic Birch is a little better architecturally. Both are good, but I prefer MDF where speakers will be set in place permanently. It is much heavier though, and it is easy to dent. And it "turns mushy" when it gets wet.
As for the options of surface mounting versus flush, I prefer flush for aesthetics but there really is no acoustic benefit. Both are fine acoustically.