No bracing necessary. And the foam that Mike mentioned can be used, or you can line it with a thin layer of R13 insulation (well, relatively thin).
And actually, 220liters @ 17Hz won't work for you with a 24" dia/36" long sonotube. The port will be too long to fit. You'll need to raise the tune to just above 19Hz. Which isn't that big of a difference. Then I'd put a highpass in at 18Hz and give 'er 1000W.
This amp would give you both. Among other things..and its on special with free shipping and has a good warranty.
Or you could go the pro amp route like a lot of other folks (including myself) go.
edit: Ah, you were already looking at the Dayton amp. Well ok then.
