Hi, and welcome to the forum! I see that you've posted this question on multiple sites, and I hope that you get it resolved. The TV model number that you posted has a typo - it's actually JLE37BC3001. That might slow some folks down.
Are you watching over-the-air TV broadcasts, or do you have some other source like a cable box connected to the TV? I ask that because it might be your source that is causing the audio issue and not the TV or its connection to the Marantz.
Turning the volume up on the TV would only affect the speakers on the TV itself or the analog audio outputs if you have those outputs set to "Variable." It wouldn't affect the digital audio output at all. As for the digital audio output, check out the audio menu on the TV and see if you have it set to Dolby Digital, PCM, or Off. I'm assuming if you get any signal at all (and my impression is that you do), that it's not off. I'd also turn SRS TruVolume off. If you're going to use the Marantz for TV audio, I'd turn the TV speakers off, too, in that audio menu.