Do you want to replace everything?
The "sub" in that system is really just a bass module, which is not a subwoofer. It's just there to make up for the complete lack of bass capability of the little speakers in the system.
Do you have a budget? Oops, I guess you provided that.
We can figure...
You can always come here, provide an explanation of your goals, and ask for some guidance in the hardware sections. That's a better way to start, by getting suggestions of what type of equipment you might want, then you can go to reviews of specific gear.