You might have to add some volume to just the center channel to match, but is common to change the center channel level anyway. If you continually play your stereo at a max level, expect that your amp will not have an extremely long life. You probably wont do this but 4 ohms is hard on recievers. They require more current to drive to 100 watts or whatever you have there. The power supply is not rated for this. The transistors will not be the problem.