K 8060 burns

The 8060 seems to me the ideal amplifier to pass frequencies between 5 and 100 Hz from a frequency generator to a 2.5 Ohm coil. This worked very well up to an output voltage of approximately 14VAC/1.35A at the 8060. After that the amplifier collapses: R4 smokes, T1 - T5 are destroyed as well as R19 and R20. Meanwhile my 3rd board is burned. Now I’m looking for explanations. Can anybody help me.
Thanks.