I would return it and try different speakers. In my 35 years of experience, cables, electronics, and speakers do require some break in. However, their characters show in the first 10 to 20 hours. No matter how long you break it in, a bright speaker won't sound warm or a warm speaker won't sound bright after the break in. Using cables and other accessories to fix the problem is the problem. Try your new speakers for more hours to see what happens. Nowadays I only buy equipment that I can try for 30 or 60 days with full refund upon return.
Speakers sound too bright.
I just bought a new pair of Martin Logan 60xti speakers. They are too bright and fatiguing. I would like to avoid returning them. I've tried toeing them in and out. I cant get them further than 1ft away from the wall (back of speaker to wall). I have a about 1-2 hrs of play time on them. Not sure if break in will help settle the upper frequencies down. Any suggestions...?