I have a set if Bose 901 series IV speakers connected to a Integra receiver both about ten years old. I want to know if I can reduce the ohms from 8 to 4. And what impact that will have on loudness and clarity?
You could wire an 8ohm non inductive power resistor in parallel with the speaker so that the amp would see a four ohm load.
However there is no advantage in doing that since any increase in power would be absorbed by the resistor not the speaker. That means little or no increase in maximum volume. Plus I seem to remember Integra receivers were rated into 6 ohms but don't think they were rated into 4 ohms.
There would be no improvement in audio quality.
If you are looking for clarity you will need to upgrade the Bose and then the receiver.