An good integrated amp with home theatre bypass is a great way to keep the 2-channel quality high in a combined system. The trickiest situation for most is how to deal with the sub. For me, I prefer to have the prepro or receiver set to a "no sub" setting. This would then direct all bass information to L&R speakers. Then you'd have the front L&R preout of the prepro or receiver going to the home theatre bypass of the 2-channel integrated amp. Then, I'd take the preouts from the integrated amp and run them to the sub and use the crossover in the sub. The front speakers play full range and you set the sub to the crossover point and level you like best for music. If you really wanted to, for the times you're watching movies, you could turn up the level on the sub and even choose a higher crossover point if you wanted more bass impact. Alternatively, there are subs that would allow for connection from two different sources (ie. sub out on a prepro or receiver and low-level L&R inputs or high-level speaker inputs from the two channel system).