I currently have a Yamaha R-XV1700 reciever, Onix X-CS Center, X-LS for fronts. I have HTD level 3's for rear surrounds because the X-LS's are rear ported and my rear speakers need to go against the wall. Now i want to add 2 more rear surrounds Should i buy 2 more x-ls's so most of my system matches or should i buy 2 more HTD Level 3's so the rears all match and the fronts all match. I heard for the rears matching is not as crucial. Any input is appreciated.