Glai:
You mentioned that side walls do have curtains, does the treble quality worsens if you open them while listening?
Also do you have any treatment in the front wall, what's between your speakers?
If front wall is too reflective or have furniture in between speakers, that could be a contributing factor to what you hear. If this is the case try placing a blanket between speakers in front wall /furniture to find if this is causing you trouble. What happened? A deeper soundstage might be a pleasant bonus in doing this.
Your feedback.
Luis
You mentioned that side walls do have curtains, does the treble quality worsens if you open them while listening?
Also do you have any treatment in the front wall, what's between your speakers?
If front wall is too reflective or have furniture in between speakers, that could be a contributing factor to what you hear. If this is the case try placing a blanket between speakers in front wall /furniture to find if this is causing you trouble. What happened? A deeper soundstage might be a pleasant bonus in doing this.
Your feedback.
Luis