I had to place one speaker (dynaudios) close to fireplace as well at old house ...thought it was far enough away and monitored and felt the side of it,it was fairly warm... but not hot...had big family gathering at xmas and fireplace got super heated... I had to get one of the woofer’s repaired because of damage from the heat,...lesson learned...
yeah the air quality was horrible as well...never got adequate air ventalation...