How To hear a setting's effect with ReaEQ

You can't. Not with one switch at least :) This plug-in soloes the band by creating hi&low cut filters around the target frequency (or predefined range, not sure), and it is also boosting the target frequency with a narrowband filter (I guess if needed) for easier allocation / analysis. e

I made a plugin a while ago. Set your track to four channels. delta_send --> EQ --> delta_receive

Thanks to both of you!