You may being opening up a can of worms here. Klipsch are much more efficient than most brands. Very few speakers out there will play the same volume levels. Can your amp handle the difference. If you like to "rock" then I highly doubt your amp can handle something rated at 3-6db less. Every 3db in efficiency that you go down requires double the power to maintain the same perceived volume.
Also, rear ports, front ports or no ports will make a huge difference on where you place the new speakers.
Get ready, this is a start to a whole new system :-) FUN
Also, rear ports, front ports or no ports will make a huge difference on where you place the new speakers.
Get ready, this is a start to a whole new system :-) FUN