What are the main benefits of having seperate amps over a high quality receiver? Is the sound really THAT much better to justify the cost? Or is there more options for upgrading along the line for one or the other? What about when it comes to just playing music LOUD for long periods of time, would one be more suited than the other? Also, how much would you have to spend on seperates or what kind would you need to outperform say like a top of the line denon?