since you've changed direction several times here. let's sum up what's been resolved.
A (power) amplifier simply amplifies. has no controls, simply one input and one output to speakers.
A pre amplifier selects sources, controla volume and is where tone controls, if any, are located.
In the case of a multi-channel system you also need a processor which takes an incoming digital signal and turns it into a 5.i analog signal. This is part of the preamp stage doe it's usually referred to as a pre/pro.
These can be bought separately but there are other ways to get these.
An INTEGRATED amplifier combines both a pre amp and a power amp on one chassis.
What you seem to be asking for is an integrated amp.
A receiver combines an integrated amp and a tuner on one chassis. These tend to be more cost effective than going for separate units.
For what you want, you need (unamplified) speakers and a subwoofer. Like you said, the subwoofer can be added later, and you are correct.
Now, all receiver I can think of offer bass and reble controls but not with the familiar twisty knobs. In some cases they are now buried In the menu system and are not as easily accessed, but they are there.
If you want a decent receiver at a reasonable price, this is a good place to shop. Good products, great price and we've used them for years with great results.
Poke around and see that will work for you:
http://www.accessories4less.com/