(This may sound like a silly question).
What does it sound like if the tweeter (and/or midrange) speakers are completely disconnected, with only the woofer without any crossover?
The only possible reference I've heard, is playing a stereo through a stack guitar amplifier. IIRC, there were...
Around y2k or so, there was a case of bad capacitors due to corporate/industrial espionage. It turned out they got the stolen formula wrong, which cause such capactors to fail prematurely.
https://www.theguardian.com/technology/blog/2010/jun/29/dell-problems-capacitors