I have a question about home theater setups.What do y’all have and would you suggest any brands to check out.

My current setup isn’t really a home theater as it is a stereo setup with a sub that i use to play music on really loud and just happens to be hooked up to a DVD player. I have a Onkyo reciever (the 5.1 one that i dont have the model number for right now) with 2 Kenwood floor standing speakers that a overpaid for on base (1″ tweeter, 3″ mid driver, dual 6″ woofers) and a yamaha dual
10″ power subwoofer. I’m looking to piece this upgrade together as even decent surrounds tend to cost a couple hundred dollar a piece/set depending on what you look at. I plan on starting this upgrade around Feb/Mar as I change bases again in Jan and will prolly have some out of pocket expenses for a apartment and such until my allowances for my apartment kick in.

oh and also, do you audiophiles have any grips about a mixmatching brands on a home theater?

Thanks for any advice y’all have.

edit:
Reciever is a Tx-sr502 (6.1 surround)