Whats the brand and model of your front speakers? I guess your front speaker is a 2 way Coaxial Speakers. Commonly, what people do is install a good component set for front speakers.

If you feel bass not enough can you adjust the level from your amp? Try not to push hard your amp level to 100%, make it around 40-60% will do. Most of the time when amp pushed to their limit, sound will get distorted.

Your woofer and monoblock amp shud do the job well, just need to fine tune it.

Ok, i am just saying below based on my experience, you dun have to follow me 

1. Get a good player
2. Change your current front speaker to back speaker
3. Get a good front component set
4. Get an amp for your speakers, 2 channel if you want to boost front only, or get a 4 channel if you want to boost both front and back.

Anyway, final setup still depend on what you like, you like good clear music(SQ)? or you like heavy bass music(SPL)? Life is easier if you like heavy bass. 

People who play SQ are very stubborn and tedious ppl.. (just like me)

Haa, i am no sifu, just special interests in ICE, spent so much before for ICE, wasted so much money as no clear guidance from friends. Most of the Car Acc Shop just wanna squeeze every bit from your pocket, most of them will tell you what to buy, but never really teach you the basic and logic behind.

Still remember more than 10 years back, I spent RM1100+ for a basic pioneer CD Player (1XXX series), a chapalang 6x9 speakers, and a cheap china tweeter. This was a pain, and if you can avoid it, yes dun repeat my mistake.

I will go back shoot the picture and PM you tonight, kept in box, never really used it. PM u price tonight.