How much dirt is too much dirt

I have no idea quantitatively. I have been pursuing high end audio for fifty years and each step with cleaner power has instant benefits to the sound quality. So, hence good quality preamps, DACS, streamers... etc, weigh 40 lbs or more, most dedicated to power management. Really good equipment will have two boxes... for instance a preamp. Direct lines, power conditioners, high end power cord all contribute to better sound. 

I payed attention to specs on equipment for the first couple years and then gave up, because by and large you get misdirected by measuring a few variables as there are so many. Hence, I never started measuring power or distortion. 

Having TV’s on usually reduces enjoyment. Seriously though, you have to try this out for yourself. Dedicated lines are a significant upgrade if that is possible for your system. I was listening to my system last night, Christmas Eve, and the sound was exceptional. Assuming there would be lower noise on power lines coming into my home due to the holiday, it made me think I might need better filtering. The folks that use the PS Audio regenerators seem pretty happy with the results, and regen seems like the ultimate resolution. 

Some knowledgeable people have said, for best results unplug everything in your video system - unplugged not simply turned off...it works in my system, and is obviously a free tweak...I'm on an excellent power grid, and power conditioning has only had a negative sonic impact for me ...