This might be the tricky part. As @Smartplug already said you probably see a massive boost in the lowest bass when you look at your PEQ filters. Some advocate against any form of boost in the correction, because "dips cannot be corrected for". However, down below 40 Hz we're probably not talking about dips due to room modes or speaker boundary interference response (unless you're living in a very large room). Extending the lower limit of room correction that much to lower frequencies will simply push your speakers harder to extend their frequency response.
This alone has it's pitfalls. Boost in EQ might lead to clipping in the digital domain unless the volume limit is reduced (I still need to investigate further in this issue). Your power amp section will have to work much harder (boosting the SPL by 10 dB requires 10 times the amplifier power at the boosted frequency!). Finally the excursion of your speaker cones will increase an thermal stress on voice coils and crossover components will increase. In short, you can gain more bass extension but always at the price of reduced maximum loudness.
Finally, it is also not too unlikely that your microphone (which one?) doesn't even measure frequencies below 40 Hz correctly. If the mic just registers a lower SPL than actually present, the WiiM room correction will wrongly assume it needs to apply boost. The result is simply an overemphasised bass.
As long as you are happy with the result (and you are aware of the fact that you're getting closer to the power limits of your amp and speakers) everything is fine. Just make sure to ask yourself it what you here now is really more natural or just more pleasing (many of us are simply more happy with more bass
). Even if your answer is the latter it's still fine if you like it better that way.
