Sub Question. One higher quality sub or two lesser quality? (Rythmik vs HSU)

TWO..or more,HSU and SVS both good as I am sure the others mentioned are too.
SVS lets you have free shipping both ways..in case you wanted to send it back,
SVS Also has 1 year trade up policy.Example,
You buy 2 PC2000[Pro version Now but they have the PC2000's at this time]..
and if later in the year you want to go bigger then send them back
and
you get FULL credit towards the Subwoofers that are higher up the price line.'
Free Shipping all the way around.
Power Sound Audio seems to make nice Subwoofers also,
I have a friend that has one and enjoys it.
He[Tom] used to be Part of SVS some years back.

congrats... and,you can a second one later on when budget presents itself