Is it 300W x 4 channels? If you are only using 2 of the 4, then no, its not going to put more power out because you are only using 2. Now if your amp is bridgable, you can combine channels 1and 2, and channels 3and4 to make a 2 channel amp. But your amp has to be capable of being bridged. If it is 300x4, then you are only getting about 75 watts per each channel..assuming that you mean a total of 300 watts for the amp..

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