My newb opinion is, buy an amp and a woofer. I am not sure what music that you listen to, but, it would be nice if you can get a 4 channel amp and a subwoofer. The 4 channel amp can be used to power your current component set and the woofer. Since I mention 'a' woofer, your amp must be able to handle the woofer in bridge mode. Meaning, if it is 2 ohm stable, you can use a 4 ohm woofer. If it is 4 ohm stable in bridge, you might need to opt for a DVC woofer. Of course, with these items (woofer & amp), you might not get the very best stuff with 1k budget. Maybe you can consider the Mohawk brand since it is quite cheap compared to others. The most important thing is, be patient and know what you really want with your setup.
Hope this helps.