Thanks for the advice. I do not intend to purchase any high-end speakers, just wanna buy an affordable studio monitor that sounds flatter. I have found that so far my top choice is Presonus Eris 4.5. I like Edifier not only because of its cheaper price, but also decent quality. Unfortunately, I realize that Edifier has BBC dip bias in midrange especially at 1,000hz to 1,500hz which is most prominent frequency range for vocals. The Edifier BBC dip is a little bit too much down to almost reduction of 10 db to these range has led to weak vocal sound from powerhouse singers such as Whitney Houston or Adele. A little dip like 3db ~ 5db is pleasant, but 10 db dip is just too much, making vocal sound unnaturally & distortedly weak. Besides, my XM6BT sounds unusually bright at 2000hz like a spike after the dip of 1000 hz ~ 1,500hz. Such disharmony is highly perceivable in the form of nasality from singers or singers having cold, making female singers sound like Celine Dion & male singers sound like Willie Nelson. Also, it's very ear fatiguing to listen from singers whose resonance boosted at 2,000hz ~ 3,000hz, they all sound unnaturally bright. My conclusion is if you are a little into vocal sound, avoid Edifier due to discoloration of lower mid-range and coloration of upper mid-range. A speaker with a flatter mid-range or slightly dipped mid-range will be much better.
I agree with your opinion as 2.1 was made for gaming therefore it will focus more on the bass as it would enhance your gaming experience that's why the audio is unbalanced. This is why Edifier launched the 2.0 series for the people to enjoy music and movies, it has a more natural balance sound unlike the 2.1.