*If* they are true, yes.
If you found them in EBay from a Hong Kong supplier they are probably fake.
Post some pictures: the Power PCB, both sides, and a heatsink closeup, to see how they are nounted.
What codes do the "small transistors" have?
EDIT: is it a Peavey Megabass, a Mega Bass guitar or Bass amplifier or a Megabass car amplifier?
Very different animals.
Also search and build a Lamp Bulb current limiter, to plug your amplifier into until fully repaired.