That's a tough one since different speakers are not going to be a perfect timbre match for your current ones. I'd try to stick with Infinity to get a close match, you can look at the tweeter and midrange driver materials to get an idea if they will be close, but likely won't be a perfect match to current models. Surrounds are less critical, so a little mismatch is OK, but a big mismatch will be noticeable IMO. Worst case, you'd want to replace the current ones and put in 4 matching new ones.