Generally it’s all about cost. A $10k integrated is going to beat a $3k separates. If you are going from a cheap integrated to a mid level separates then you’re on the right track. However, you could also consider a mid or high level integrated as well. Nowadays there are many good integrateds from various companies available for you to choose from. Gryphon, Vitus, Pass Labs, etc. and the list goes on.
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!