To Equalize or Not to Equalize

I'm not ANTI-EQ, at all, especially when used in the sub woofer.  However, this sounds more like your room is too reflective.  This is a level dependent phenomenon we cover in A'gon like, monthly.  things sound find but some recordings start to sound harsh if not distorted at higher levels.  

The reason is usually that the room is too bright.  If you can experiment with this for free I encourage you to.  Put some absorbers up along the walls and you'll notice the harshness goes away AND your speakers will sound bigger than they used to. 

Bright or harsh could be at several different frequencies. I have Klark-Teknik 31 band equalizer in my system. I think it is DN360 or DN370. It is a studio equalizer. It sounds amazing. If you do not have xlr, you can get some nice xlr to rca at Moon Audio.

You can download Spectroid app on your phone and quickly see where the nasty frequencies are. Good luck.

Throwing in my vote for the Loki Max F. 

I have a Schiit LOKIUS 6-band EQ, signal coming from a LAIV Harmony DAC then out to an Emotiva pre-amp to an Advance Paris power amp.  You can flip a single switch and turn the Schiit’s EQ off to A/B test your results. I’ve found my Buchardt E50s need just a touch of boost in the BBC dip range. 

@erik_squires +1 sort out room first, then maybe an equalizer. Seems a more balanced solution than to cut off frequencies.