The best is to decide what your long term plan is. For me, I have two main systems. My stereo system and my home theatre system. I went to separates for both of them a long time ago and I stick to A/B amps. For example, in my home theater, I upgraded my pre-amp twice, and my speakers twice, but, the old ADCOM GFA-5503 three channel amp, and the old ADCOM GFA-585LE 2 channel amp from the 90’s are still in service - but, I did have to service them because of their age and some leaking caps. If you plan to go separates step by step, then, using your AVR as a preamp, and starting your journey with amp separates with a lot of power that you plan to keep for a super long time is for me the correct way to start. This is exactly how I started with my stereo system. I bought the one ADCOM 585LE and used my old Sony Receiver as a preamp. When I build my first home theatre system, I moved the ADCOM 585LE to the Home Theatre and bought a matching 3 channel amp. In the mean time, I decided to go to two McIntosh MC275 tube amps for my Stereo, etc.... So, separates can give you a lot of flexibility - especially with amps, which you can keep for decades.
Moving to separates
Does anyone have an experience they'd like to share about going from just an AVR or integrated to using external amp(s)? My Integra AVR has 100 W per channel (class AB), all channels driven, and sounds very good, so it is not clear to me that there is any advantage to connecting its preouts to a separate amp. Might be a total waste of money. Please mention your specific equipment. Thanks!