Impedance effect on active low-pass filters?

Think of the op amps etc. used in the active filter as a built-in buffer.
One op amp will be at the output, having a source impedance of a few ohms.

So nothing external to the active filter circuit will affect its response.
Even if the power amplifier itself is configured as an active filter.

That's their biggest advantage: unlike passive crossovers, active crossovers have no direct
interaction with the drivers, and can be designed much more precisely.
 
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