adding center speaker to existing stereo system

you should just add 2 more speakers for the left and right rear for your system. this is how my setup is.

I submit having a preamp that has HT bypass is the best way to combine 2-channel with a surround system. When I'm listening to music my surround components are off. When I'm watching a movie I use my preamp's HT bypass. My 2-channel amp continues to drive my fronts.  I turn on my Marantz AV processor, ATI 3-channel amp and OPPO 203. My 3-channel amp drives my center and rear speakers. 

HI @tls49  You make a good argument, but it's not complete.

Turns out, a center channel can really be helpful. Have you ever noticed a change in tone when an instrument pans from left to center? It turns out that right in the center your head plays a part in cancelling some of the sound. Early recordings were actually 3 channel, and man, do they sound good. :) 

So, for movies and dialogue especially, a center channel will sound somewhat better than a L and R phantom. 

Best,


E

Erik, you certainly have the right to your opinion, however, I only agree with it for one particular scenario.

I worked in the A/V industry for ~25 years, mainly dealing with mid to upscale products. The latter 15 years was spent with increasing time designing custom home theater and supervising the install. No doubt I have listened to more and a wider variety of home theater than the majority of the people here. From that experience, to agree with your comment, the center speaker would need to be identical to the L & R, not just timbre matched, but identical. Also, it would need to be driven by an amp channel identical to the L & R. The closest center speaker to his L & R is the Olympica Center, however since the OP is talking an A/V receiver for the processing and power, that just doesn't make good sense. Then use a speaker more suited for the A/V receiver, and that will do more harm than good compared to phantom center. Now if he wants to get the Olympica Center, another REF600M monoblock, and a nice processor, that would likely work ok, otherwise, I'll stay with my original recommendation.

Some of the best sounding theaters I did, regardless of price, used all identical speakers with high quality identical amp channels.

tls49 is right. it is pointless to add a speaker different in brand etc from side spkrs if you are going for high end sound. i did it, trust me.