I have a Samsung HT-F6550 Blu Ray Home theater system. I wish to change the rear and center speaker (3 ohms) with Yamaha Rear & Center Speaker (6 ohms). Can I do this directly ? Will this produce better audio ? Will this changers affect my Samsunvg Home Theater system ?
Are you trying to change the speakers to the same rating as the existing speakers or are they rated higher? If the latter, I'd advise against doing so. If the former, I'd still advise against doing so.
It is safe to try. You will have to balance the speaker levels to match properly with the original speakers.
You may not notice much if any difference from the rears in most surround modes.
The center is another story. Even if the center is better than the original one it won't match the left and right front speakers.
You might get a better result replacing the three front speakers with the Yamahas. If the original front and surround speakers are different then you can use the original fronts as surrounds.