Get the best sub you can afford now. Get another later if you don't have enough $$ left over ...
I wanted 12" drivers minimum for my sub(s) so I was only able to purchase one - the best 12" sub I could find. It helped a lot, filling in the last octave for a much fuller sound. I started saving again and eventually was able to purchase a second 12" sub. Now the sound is awesome! With two, located sort of kitty-corner from one another, I am able to get an even smoother and deeper response than with one. Now I get within +-3dB to 20Hz. Dual subs (or more) is the way to go, fur sure!
I wanted 12" drivers minimum for my sub(s) so I was only able to purchase one - the best 12" sub I could find. It helped a lot, filling in the last octave for a much fuller sound. I started saving again and eventually was able to purchase a second 12" sub. Now the sound is awesome! With two, located sort of kitty-corner from one another, I am able to get an even smoother and deeper response than with one. Now I get within +-3dB to 20Hz. Dual subs (or more) is the way to go, fur sure!