The 1200w should be max power and won't be powerful enough to power a sub. Provided that your HU has 3 pre-outs or you have pre-amp or electronic crossover, then add another amp for your sub. This is the most simply way to add a sub.

Wiring maybe got problem?
Anyway with rm1k you cannot do much, the most is a 2 ch amp, a 12" sub(rm400 each) then a passive crossover which is a coil that cost you rm80-rm150. This coil is use for reducing noise going into sub thus you have more solid bass, as the 2 ch amp sometimes its low pass filter cannot filter out all the voice. You can try with and without the coil. With coil the woofer's movement is less compare without coil that moves very fast. If get e-crossover will sure burst your budget of rm1k.

This post has been edited by jojo902156: Oct 5 2006, 11:15 PM