If we limit the discussion to true subwoofers as opposed to add-on woofers, then there is absolutely no problem with down firing subwoofers. For instance REL touts their 2 channel oriented subwoofers as sub-bass systems. They are specifically designed to add not bass, but deep bass to existing full range speakers. A down facing driver is an excellent solution for such a situation.
Regarding subwoofer amps, it's just like anything else, some are crap some aren't. A dedicated sub amp doesn't have to be the most refined amp because it's only handling low frequencies where harmonic distortion is harder to hear and less offensive.
My experience is that two subs are better than one, but one great sub is better than two good subs.
Earlier today I saw that someone was selling a Monitor Audio sub for less than $500. They are great subs for music. BTW, they have both forward and down facing drivers.
What do you think of the Norhs?
Regarding subwoofer amps, it's just like anything else, some are crap some aren't. A dedicated sub amp doesn't have to be the most refined amp because it's only handling low frequencies where harmonic distortion is harder to hear and less offensive.
My experience is that two subs are better than one, but one great sub is better than two good subs.
Earlier today I saw that someone was selling a Monitor Audio sub for less than $500. They are great subs for music. BTW, they have both forward and down facing drivers.
What do you think of the Norhs?