Well of course there's not enough info here to make a complete assessment of your system, lifestyle, etc, and what you do and do not like about your system.
Still, the first thing I'd recommend is that you do matching speakers all around. I'd add matching fronts to your center and rears - even if that means leaving your current mains for 2 channel only dubties. You MUST do matching all up front. It's the same as having a mis-matched left and right speaker for stereo! Basically, you wouldn't do it. You'll never have a coherent, quality sounding multi-channel systm that dissapears into the sound stage. Quality over quantiy...every time.
I know people day dream about building a theater system around their beloved stereo speakers they love so much. But, the reality is is that it's all about "the team" when doing a system. And you can't mix and match on the speakers, and expect great sound. No need to reinvent the the wheel here. Ask any pro, they'll set you straight here - trust me.
Beyond that, you can also upgrade sound quality to latest HD codecs, EQ technology (Audyssey?), etc, with a new pre-pro. Dynamics also improve here with this upgrade.
I would also make sure you'd doing Blue-Ray, have your speakers all setup where they sound the best in your system, relative to your seating, acoustics in order, all levels set properly.
Another often overlooked parmeter, that affects dynamic range, is making sure you're doing proper bass management considerations. Simply running even large speakers full range - simply because they can be run full range - is a mistake! Cross the speakers up higher from a subwoofer is a much stronger dynamic pressentation, considering all speakers setup properly in the room (avoiding nasty holes and such in the response curve, near the crossover points, to be sure).
Beyond that, can't speculate on your sources, wiring, room layout, acoustics, lifestyle habbits, relative current equip setup choices, etc. Pehaps an update?
Still, the first thing I'd recommend is that you do matching speakers all around. I'd add matching fronts to your center and rears - even if that means leaving your current mains for 2 channel only dubties. You MUST do matching all up front. It's the same as having a mis-matched left and right speaker for stereo! Basically, you wouldn't do it. You'll never have a coherent, quality sounding multi-channel systm that dissapears into the sound stage. Quality over quantiy...every time.
I know people day dream about building a theater system around their beloved stereo speakers they love so much. But, the reality is is that it's all about "the team" when doing a system. And you can't mix and match on the speakers, and expect great sound. No need to reinvent the the wheel here. Ask any pro, they'll set you straight here - trust me.
Beyond that, you can also upgrade sound quality to latest HD codecs, EQ technology (Audyssey?), etc, with a new pre-pro. Dynamics also improve here with this upgrade.
I would also make sure you'd doing Blue-Ray, have your speakers all setup where they sound the best in your system, relative to your seating, acoustics in order, all levels set properly.
Another often overlooked parmeter, that affects dynamic range, is making sure you're doing proper bass management considerations. Simply running even large speakers full range - simply because they can be run full range - is a mistake! Cross the speakers up higher from a subwoofer is a much stronger dynamic pressentation, considering all speakers setup properly in the room (avoiding nasty holes and such in the response curve, near the crossover points, to be sure).
Beyond that, can't speculate on your sources, wiring, room layout, acoustics, lifestyle habbits, relative current equip setup choices, etc. Pehaps an update?