go to the sound setting in the user menu, and make sure the auto sound is on and the srt surround is set to off, also check the equalizer and set the first 2 settings to 1/4 the level and set the last 2 settings to around 3/4 level, this will optmize the sound, I recommend to get a surround sound system, and if you do get one, always set the mute to on in the sound setting, if you don't mute it, and only turn the volumn down you will get feedback through the speakers
Does the LN52A550 have level sound? And if so does the optical out from the TV also have it. The high volume of commercials is about to make us go deaf. If no I'll be looking for a new home theatre amp.