Amplifier installation in 93 – Experiences?

Hello. The audio system from Saab is not the yellow one from the egg. At high power output, the frequency gradient breaks away and basses start to bubble, voices overturn and the driver gets a thick neck. Why do my very good PC speakers have to be much clearer and lighter than the Saab Radio? On the speakers it is no longer possible, they are upgraded (Infinity Reference 6502i front/9603i rear). The tricky should be the Saab Ra. In the lower area I am satisfied with the sound. So I was in the attic earlier and brought down my good old amplifier from my late Bulli. I wanted to see if I could get the physical/covered built-in tomorrow. The mass is 33x26x6.5 cm. Someone has already gained experience here. The amplifier doesn’t fit into the place of the AS3 amplifier. Under the seat maybe? What NI CHT should be: – Mounting on the rear seat. – Mounting in the hollows behind the wheel boxes.