I'm planning on buying an inexpensive LED-LCD TV in the near future (I'm a late adopter, to put it mildly), and I wanted to know whether it would be safe and effective to connect the headphone output to an auxiliary input of a stereo receiver, in case I'm not satisfied with the TV's audio section. So, I searched the internet for advice on this, and found none. I continued searching using different approaches, and eventually got the answer I wanted by stumbling onto a block diagram by Texas Instruments of a "typical" HDTV. According to it, the headphone output is driven by a dedicated headphone amplifier IC. These are low power analog ICs with impressive specs that get their inputs essentially directly from the TV's DAC outputs. However, audiophiles who spend hundreds of dollars on outboard processors that make use of the TV's SPDIF output would probably cringe at the notion of using the headphone output for anything. The trick is to get the best gear you can afford, make the most of it, and turn the volume down until it sounds acceptable. However, no matter how much you spend on TV audio gear, the audio quality will often be limited by the poor quality of the broadcast signal, which periodically shows signs of excellence.
So, the answer to my question is that there's a GOOD CHANCE that I will be able to drive a receiver with the headphone output and obtain satisfactory sound quality. However, before doing so, I will check my TV's manual and perhaps get a schematic. My greatest fear is that the headphone amp would be Class D (although this is highly unlikely), and that something might go wrong with it and fry my receiver's input. Well, that and the collapse of civilization.