I have various Powersoft amps that can do FIR, but this time I wanted to test something on a pair of active speakers.
Looks like it will be either a Apex IntelliX or just a DI box on the amp output with 40dB pad for this test.
Such setup is too much complex to have a reliable result : )
Any convolution plugin can serve this function. I can help you with one.
But most important thing is not a fir filter as processing unit but how to create its coefficients.
This is very tricky because the power and possibilities of fir are so high that it may "destroy" your system.
The predistortions of fir EQ (any EQ as well) must be respective to distortions of your system. They will compensate each other in such case.
Otherwise, you will have new additional distortions created by improper EQ.
How do you create fir for your test?