I currently have JBL N28's in front with N-center and N24's for surrounds with a SVS 20-39 PCI. I'm thinking of upgrading to something that will have a little better clarity, detail, and get a little louder. I'm running the speakers with a Denon 1803. I have a cabinate custom built for the N28's and N-center so that it completely encloses them. Would this mean that i can't get rear ported speakers? Or would I have to have a space abopve the speakers for the air/sound to escape. I'm looking for 5 new speakers for around $750. I was looking at Dahlquist(QX6 front, QX4 surrounds, and matching center) or Ascend Acoustics. They're both rear ported but are shorter than the JBL's, so there will be that space above. Any recomendations on speakers that will be clearer, more detailed, and louder than what I have right now would be great, thanks.