Hey guys, Hoping some of you can chime in on this.

Ok so I managed to pick up an Alto PA system.2 Alto Elvis 15" Tops and Alto Mistral 900 Poweramp (2x 300w at 4ohm, 2x 190w at 8ohm).
They sound frickin absolutley fantastic!.But i was looking into getting a a Set of Subs to 'biggen' up the sound.

firstly i'm torn between a few options.

1. Pair of matching Alto 15" Subs, Which may not be the best since thats alot for that not so very powerful amp.

2. 1 Matching Active Alto 15" Sub for the time being (no speaker out on this one, so it would mean i would need another active Sub to Expand i.e. not so versatile a Rig)

3. A relativly inexpensive relativley powerful poweramp (http://www.musicstore.de/en/PA_Homer...usicstore.html)
with a pair of Subs (not sure which Subs yet though,mabye some suggestions if you like this option? thankie )

4. A relativly inexpensive relativley powerful poweramp (as above) with 1 Dual Sub, Either 2x15 or 2x18.possibly this(http://www.thomann.de/thoiw6_yamaha_...cd69c7750beb54) yamaha dual 15" Sub(tho doesnt seem to have internal x-over and pumps out 33 Hz-2 kHz, not sure if that could become a problem or anything?) This option would mean I could simply put it vertically and stack 1 Top on it and use the other on a stand.

If you guys have any other ideas i'd be glad to hear it

i don't have a super big/don't want to spean alot/ on the Sub-side of things(as i've heard one should really put the vast majority of thier money on quality tops and that high quality subs aren't all that necessary, or am i wrong?)

Thanks alot!