Hey Jeff,
I have a pretty strong opinion regarding this, based on experience and basic understanding of 2-Channel Audio and HT. I'm not saying its the correct answer, but at least it's well thought-out.
If you want great 2-channel sound quality, build a great 2-channel rig (first priority), then add HT to it.
This opinion is based on the fact that when listening to 2-channel you are most critical of the sound only. However, when you are doing HT, your primary sense is visual and the sound is secondary. You don't necessarily focus on the sound like you do with 2-channel audio.
That said, how do you build a 2-channel system, then add HT? Well, build the 2 channel rig (pre-amp/amp or integrated amp, source components, front L&R speaker). Once you have this in place, and you're happy with it, add HT. To do this, it's easiest to use an integrated amp, or pre-amp/amp combo, that has an HT bypass/processor loop. And on the HT side, your HT receiver would need to have pre-outs for either the front L&R speaker, or all speakers. You would connect the front L&R pre-out to the HT bypass/processor loop input on the Integrated Amp or pre-amp using a pair of RCA interconnects. Once you have this all connected, you would need to run your HT receivers setup routine again to account for the possible difference in the sensitivity of your integrated amp/amp, vs the HT receiver.
So, to listen to 2-channel audio, you simply need to turn on the 2-channe rig and source and play music. The HT receiver is not even in the circuit and it doesn't even need to be powered on. To play HT, you would turn on the HT receiver, select the source, choose the HT bypass input on your integrated amp/pre-amp and play HT.
It's easier than it sounds and once you understand it, it's really simple and easy. It's also the best way (IMHO) to get great 2-channel sound quality and also have great HT, using the same pair of front speakers.
Regarding your desire to have a streamer for digital audio, I would simply add a Bluesound Node 2i to the setup. It's $499 and by nearly all accounts it is a screaming value.
So, what do you need? An integrated amp (or a pre-amp/amp combo) that has an HT bypass/processor loop, and a Bluesound Node 2i. You can actually get by without the HT bypass, it just ads a touch of complexity.
Sorry for the rambling post. If my explanation confuses you, feel free to ask questions. I've had this type of combo system on a couple of different occasions in a couple of different homes. Works great.
