Re: best size speaker for vocals
If you add another set I would say that no matter what you add it is going to sound worse. Adding more speakers isn't the key to better sound. Usually, less is more as far as sound quality goes. Less speakers means less cancellation, means less peaky response means less annoying resonances that lead to listening fatigue. It's also less amp channels you have to worry about, less wire you have to run and less speakers you have to find a place for. Furthermore it's less money you have to spend on speakers and all the other above support stuff for them.
Plain and simple better sound with less, pretty much a no brainer. Get one good set of components for the front and power them well. Rear fill is up to you, but I and many others here don't like it. The money you save on all the other stuff you can spend on a better set of component speakers.
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