I have a simple entertainment stereo with 2 speakers and a sub. Similar to thishttp://www.google.com.au/imgres?imgurl&i… but not as fancy. Could I change that sub woofer over to a better sub woofer that has a higher RMS rating to make it sound better, if it is the same Ohms as the original etc... Will I hear more Bass as my one is currently very "flat" you can't hear any "doof" with the music. So again can I get a better sub for that system or will it be limited by the driver in the stereo itself.
Can't be done with shelf systems. They are not designed for such substitutions nor additions
I agree. The best you can do is try to change the placement of the subwoofer to give smoother, tighter bass at your main listening location.
When you upgrade - get a full-sized AV Receiver and a self-powered subwoofer. This gives you both placement and upgrade flexibility.
Well you said it, it's a simple system, which is probably good value for money, but it is cheap. If you want better you just have to buy a more expensive system. Good and cheap seldom come together.
If you want to save money, you'd do better to take a chance on a used, medium quality system, rather than try and boost one part of a budget system.