Can you be more specific on the problem? Can you actually HEAR the local stations but get the hiss as well?
It almost sounds like the input gain to the receiver is way too low. For example, if you have a cable box, and use the cable box's menu to lower the cable box volume (not the TV's volume, but the cable box), you'll really have to crank the TV volume to get the sound to come out. But since you've really turned down the gain to the TV from the cable box, the TV's own audio amplifier has to try and boost the very low input signal. And in doing so, the "noise floor" is going to be amplified, too. Hence, you'll get a lot of hiss and other undesirable sound.
So please be more specific on what's happening. Can you at least hear the radio stations? Do you really have to crank the receiver volume?