My setup is win10 laptop running Roon and REW connected to ADI-2 DAC, which feeds two NC400 amps.
What would be a good way to check the results of the REW filters?
REW can generate filters in wav format and IIRC there is a way to load them in Roon. You should also take care to apply fitler attenaution in Roon equal to max filter gain which is specified on upper right corner of REW's EQ window. Attenuation wouldl probably differ for left and right channel fitlter so in Roon you should use larger of them for both channels.