[kengrayfield]

Thanks for all the replies. My speakers are actually rated with FR from 45hz to 22khz. And stupid me, I have adjusted the curve with full-range speaker option the whole time. After choosing "bass limited" option with cutoff at 40hz, there are actually at least four peaks found below 50hz range. Hope this means that the IR will be helpful in my case. Also, I am only using this for my stereo setup, fed from my PC through toslink to an external DAC.