Easy Hoss; you might want to open your mind up here a bit.
Let's understand that each 1446 is spec'd @ 75 watts each/300watts for four. That is clean, usable power out - according to the people who mfg the part an well as providing to the engineering community with the data sheet to create applications. That is using 12.5v, so at 13v (not in specs with the data sheet BTW), it will start putting out a little more power. But also starting to add some distortion/harmonics just because you used 13v; 13.8v will have even more. Transistors are notorious for doing just that.
Now, lets add more input power than they were spec'd for. They are spec'd for 5 watts/ea; so a total of 20 watts peak input @ 13v using four transistors with some distortion should put out 320 watts. That is almost 10% added distortion from the spec'd 300 w/o distortion.
Now, if you drive it with 40 watts, not only does the distion rise to 30% or more, but you run the risk blowing those transistors and will need expensive repair because you wanted some more watts. Extra cooling will not help, because inside the transistor at it junction will get hotter/faster than the heat sink can cool them.
Just a matter of time . . .