I am curious about line conditioners.

I'm sorry, no need to goto tech first just type it in. Also try 'power' and 'power conditioner' I did the very thing I'm suggesting to you just last night.

I am amazed with my PS Audio P600 for my Pioneer HD-710 and front end equipment. Everything has more definition and placement. I did visual testing with no sound and only after a few comparisons did not want to watch without the P600. I have owned the Tice power block and others but found they were dispensible. This is what I always wished was available to the audio/videophile for years. Also using a power plant seems to let the equipment come through and not add any of it's own sonic signature to anything.

I also found the biggest improvement was in the quality of the video in every respect. I also experienced something similar to Elizabeth. For fun I connected my Vansevers Reference conditioner from my audio system to the Video system and found the colors became too vibrant, almost cartoonish.
I probably could have adjusted the settings on the TV to tone it down, but it was already perfect with the conditioner I was using (Audio Power Pack II).

PS: I recommend you get a conditioner with dedicated Digital AC inputs. The Video will perform best with digital AC conditioning from my experience.