You have a TTS (Typical Tenore Syndrome) man!
It has no stability. It happens and goes away after some time... without any signs, without any reasons, without any explanations you don't know how long will it last or how long will it take to cure.
Many people suck their Tenore's holes (yes both front and rear ), many people removed the filters, many people played around the cable and connections........ NO CURE, NO OUTCOME!
That TTS will make any Tenore lover a paranoid listener
LOL LOL SO TRUE SO TRUE!! TTS IT IS!!!
p.s. I ended up just using my AM-90's with bass boost, and gave the Tenores a rest for the night.