Hello, I have a Onkyo TX-DS838 receiver. I really like this receiver except the output on two rear channels, only 50W. It’s hardly to hear something from those two rear speakers. My question is: Is that possible to attach these two rear channels to an amplifier in order to get the same output as two front channels, which is 100W? Any suggestions about what find of amplifier can handle this well? I don’t want to put in a lot of money for this upgrade since I’m going to replace this receiver with a newer version. Thanks.