Both subs are pretty much the same in output... with the Ultra13 pulling away in the lower regions, while the Plus/2 has a touch more lead in the greater then 30hz range.. Its negligible as to which is better... As stated before, you have a freaking huge room... like me...
If I had my choice between the 2 I would go for the Ultra13, as it has more tuning capabilities down low... the Plus 2 has a native tune to 25hz and you can tune it lower, but it will struggle more in a lower tune, because the box could be bigger. But its still a great Sub...
The Ultra13 has a native tune of 20hz all ports open, and selectably tuned to 15Hz, 10Hz and sealed settings, for your choice in depth. The Ultra is the newest driver for SVS which is IMO a much more capable, better engineered product... Driver manufacturing has come a long way in the last couple of years.
Ultimately in your really large room I would go for 2 subs, or add one later, like 2 Ultra13's or 2 Plus/2's... Don't forget to watch the
B-Stock Page, they will show pics if there is damage, otherwise they were just demo's or returns which work perfectly.
There are other alternatives too... You could do something really cool like get a couple of
eD A5 - 350 Subwoofers (unfinished) and have some local guy veneer them with whatever flavor veneer you choose. and they could match your speakers if you like. that would be $1200. delivered and whatever it costs to have someone finish them for you... Now that would be really cool 2-15" subs would have some great output...
Just another thought...
Good Luck with your descision...
