Television as source component

I fed my RCA 26" (from 1995) stereo tv variable line outputs into my computer soundcard a few years ago to capture two songs from the Burt Bacharach special that came on TNT (Turner Network TV.) The sound was outstanding !!! I was very suprised. I'm not sure if TNT always has good audio? I know that VH1 and MTV have terrible audio.

Curbach - the quality of the audio you will get from your
TV's audio outputs will depend on the quality of the output
quality from your TV's or VCR's tuner. Some do a very decent
job; and others are just plain bad. And amazing but true -
the cost of your set or VCR often has little to do with the
qulaity of audio you get.
I'm currently using a two year old Sony 32" TV/Monitor -
the model just below the XBR series - and while the picture
is great (I set it up, as I own a video editing studio) - the audio quality is just so-so. On the other hand, I used
to have an 10 year old RCA Colortrac; and the audio was
wonderful.
So look around, and seriously listen to some sets. Also,
keep in mind that some networks - such as ESPN, TNN, and
CBS tend to have better sound than others.

instead of use TV as a source component I use
Cable TV box audio outputs connected to my pre amplifier.
I use RCA cable.My prefered cable for this purpose isOxyfuel inter connects solad on internet ebay for about 70 dollars.
The cable TV or satellite box got few settings
Compression.;No need to use it as it restricts the dynamic range
Set the cable tv box to optimal stereo level.
I nee no advantage in using matrix stereo.
The cable TV box is few years old.I cleaned the RCA jacks with De oxand it effectively removed the muck and oxidation.