Very basic stereo versus 5:1 question?

"I suspect those processors also send .1 to speakers designated as large or full range if no sub is specified in the menu"

May or may not be true; I was pointing that out so the OP could check for sure. I was thinking along the same lines as Kal, that there is no reason for that to be true, unless there is some quirk in the DSP or bass management software that does not route the deep bass to the fronts in 5.1 if there is no specified. Of course since the OP never specified that he was using a sub or a center, it's also possible that in 5.1, he was NOT routing the deep bass or LFE channel to the fronts. Another possibility is that he had (mistakenly) identified the fronts as small or otherwise fooled the bass management software NOT to send the full range signal including the LFE channel, to the fronts. I will admit that Kal is WAY more knowledgeable about multichannel than I am.

Mark,

Kal (KR4) is correct, there is and should be no difference with some caveats.

The Bryston doesn't have room correction but for others to note, processors/receivers with room correction do not have the ability to apply that to the analog inputs (Anthem processors do this and are a rare exception to the rule). Having room correction turned off or unavailable will sometimes make the bass level seem greater but you are experiencing room boom and gain at the expense of bass clarity.

The second item is to make sure that you don't have the bass controls enabled. When you switch inputs/sources, you may have engaged the bass and treble controls.

Third, I have noticed that digital outputs vs. analog outputs for Cable set top boxes are all over the place in quality difference. The analog inputs are very different in their sound than the digital. I think that what you are describing is an issue with the TV or set top box analog settings vs. the digital outputs.

I don't think it's an issue related to the Bryston. It's the analog vs. digital outputs at the source.

Thanks for all the input. My fronts are set to large. I do not run a sub. I do run a center channel. No bass controls enabled. My Bryston is out for repair. Once it returns I will do some experimenting based on the possibilities mentioned.