Nothing wrong w/ buying used provided you're not overpaying and have accounted for all the factors, which is not always easy/straightforward, especially w/ a subwoofer that old.
Yeah, I found that too, but I wonder if there wasn't just a typo in the manual (as unlikely as they might seem at...
I'm not an expert or anything, but my educated guess is the biggest advances in speaker tech/design would be in the extreme highs and lows of the FR spectrum, especially the (extreme) lows, ie. sub-bass, me thinks... as that's always been the most difficult end of the spectrum AFAIK.
And I...