I'm using the analog audio outputs of the 3510, which go to the TV. Then from the TV's headphone line out, I go to an external amplifier.
But with the TV's volume cranked all the way up, as well as the amplifier's volume control cranked all the way up, I just get medium loudness. Though far from quiet, it is easy to have a conversation over it, or drown it out with a noise such as a vacuum cleaner.
How do I access the audio output level of the set top box? That would be the only place in the audio chain where I can get any more gain.
The remote control is programmed with my TV's protocol (this was kindly set up by the Shaw installer). The remote's volume up/down buttons control only the TV's audio output, even if the remote is put in CBL mode! I see only the on-screen volume control display of the TV, regardless of mode.