Since HT has been mentioned a couple of times, with regard to Sound Quality, here's a solution. Build your quality 2-channel setup, using either an integrated amp, or seperate amp/pre-amp. If the integrated amp, or separate pre-amp has the HT bypass/processor loop output, you can simply add all of the HT functionality by connecting an HT receiver's front L&R pre-outs to the HT bypass inputs of the integrated amp/pre-amp. Now you have a dedicated 2-channel system without any compromising HT hardware in the mix. When you want to play HT, turn on both the 2-channel system and HT receiver, select the appropriate inputs, and off with go with multi-channel HT.
This type of combo system works like a champ. There is no compromise with the 2-channel sound quality. There may be a slight compromise to HT sound quality performance, based on the HT hardware you use, but you likely won't notice it, or hear a difference. I don't currently have this type of combo system set up, but I have had it on multiple occasions in the past. If I recall correctly, @erik_squires is currently using this type of combo 2-channel/HT setup.