Hello All ........... I use to have a old pioneer stereo system to this day I wish I did not sell to buy my home theater in a box system but having a baby required to free up some space in my small living room as the speakers and entertainment system were way to big. anyway I finally got around to finishing my basement and still have the entertainment system and hooked up the JVC HT system down there. at the time I bought this which I regret 1. I needed to save some space and was limited on money (still am) so now that I have got that out of the way here is my dilema..... the system I bought was the JVC home theater in a box model tp-450 ? with a RX-6018 vbk receiver that puts out 120 watts/DTS/DD 5.1 blah blah blah ........... it came with these awful tiny speakers but was very happy with the 120watt 12' sub that came with it and quite suprised how well it performs given the $375.00 price tag I paid for the whole system. anyway now that you have the specs here is more. like I said I am not happy with the 5 tiny speakers included with this system, they sound hollow, tiny, and have no punch (I didnt expect them to). I was wondering if the front left and right and center speakers could be replaced with something with more punch. well last summer I tried to replace the center speaker with a cerwin vega 5 1/4 drivers and a tweeter to get a less hollow sound from the dialog and more of a fuller sound. well it didnt work as the sound comming from that speaker once hooked up was very garbled and distorted at any volume. so I brought it back. I dont know if it was me that made the mistake of not playing with the reciever speaker settings as it has a crossover setting and a small or large speaker selection. heres one thing to consider........... the directions say to switch the crossover settings to 80-120hz if you have 4 3/4 inch speakers (12cm) @ 80hz, 3 15/16 inches (10cm) @ 100hz and 3 3/16 inches (8cm) @ 120hz. so it looks like Im limited on speaker sizes or if anything replacing just the center seems to be a problem. now I dont know if the last center I purchased was a problem I made by not tinkering with the settings but maybe someone out there with these boxed systems or this system in particular someone has knowledge about when trying to upgrade the center or any others. Id hate to buy a new system and sell this one on ebay but if that the route I have to go to be happy fine but there isnt much out there for under $500.00 !!!!!!!!!!!!!!! HELP!!!!!!!!!!!!! BTW: when I did free up some space in my main livingroom by selling my large system my dad bought me a Bose wave radio to put in the nice tv stand peice of furniture he also bought hooked up to my pioneer dvd player and 27' tv. I gota say this bose radio blows away my JVC HTIAB system but thinks it also helps I have a small living room upstairs and man I can feel the bass from this small little thing and does great for a mini HT upstairs! hahahahahahaha it doesnt blow it away but it is impressive for such a small peice of audio technology. something I did leave out was that I did purchase soem 14 guage speaker wire to replace the junk that came with it and bought AR digital coaxial, s-video, optical cables for the system which made a little difference and figured it couldnt hurt. (I found it all cheap online) didnt overpay!