If you connect only the analog cables to the tv, you will only hear sound from channels that use analog audio. With TWC (at least here in Texas) the digital channels all have an analog feed also, so you should be able to hear all channels if you do it that way (but it will always be the Analog audio).
If you only connect the digital output to the receiver, you will only hear digital audio when the receiver is on and nothing from channels that are analog only.
Your best bet is to connect both analog and digital audio from the set top box to the receiver. The receiver will automatically choose the digital audio over analog if the station transmits both. For stations that are analog audio only, obviously it will choose the analog connection. This is how mine is setup with TW Digital Cable and it works flawlessly - the Onkyo 502 switches between the analog and digital feeds instantly with no perceptible delay.
If you really want to be able to watch TV without the receiver on (why anyone would want to do that is beyond me.
), then run the analog audio from the set top box to the TV, run analog audio from the TV audio out to the receiver, and run digital audio from the set top box to the receiver. When the receiver is on, you will get digital or analog audio according to what I described above. When using just the TV, you will get Analog audio only.
