I have already tried stacked and yes it is absolutely insane (this was with the 15's though)...I can't do it that way cause at low volume my house shakes like crazy and would be afraid to break everything if I stacked the 21's and cranked the volume.
I found that one per corner really flattened the sound and I like that. The drawback of having one per corner is that the bass volume goes down. I have to increase the sub out volume to compensate...hence the reason why I upgraded the amp and decided to go with subs that can handle it and then some.
I think I made the right decision but with these subs I now notice what in phase and out of phase can do!
I need the solution between these 2 and I'm really hoping the MiniDSP will accomplish that.
I could only stack them in the back too as I do not have room in the front to stack them cause my Left and Right speaker is on top of the subs. Right now I only have 2" from the top of my speakers to the ceiling.
I'm really hoping that the MiniDSP fixes my low end issues.
Right now I have the rears connected out of phase cause I crave the deep stuff.
Connected this way I also have to increase the output from the 10000Q.
In phase I have to set it @ 12oclock
Out of Phase I have to set it @ 2oclock
There's no way I'm buying more subs!!!