SMSL AD18 Sub

[Indica]

Few questions I have:

1. Best Subwoofer for under 150? I assume I'd need a powered one for the AD18.
2. I'd like to be able to control the volume of the sub, I'm not too sure if the volume is adjusted on the 3.5mm or not.
3. If it doesn't, I know I can find a sub with speaker out on it, but does passing it through the sub affect the wattage going to the speakers?

T.I.A

 

[Haint]

Dayton Sub 1200 is pretty unanimously considered the best in that price range, but I can't offer any assistance in the hookup or operation with that style of amp.