I believe speakers and cartridges should be commensurate with the electronics.
However, this thread is about the sound quality of AVP's or AVR"s compared to separates.
What are some AVPs you've looked at (at least online)?
Personally, I've listened to many ultra high-end preamps from ML, Bryston, Krell and they don't sound any better than these new AVPs (Yamaha, Marantz, Anthem).
And if you have an Atmos/DTSX system with overhead speakers, these AVPs will probably give you better sound with the awesome upmixing of NeuralX for 2Ch music.
I've sold all my SACD, DVDA, DTS CDs and I now think that NeuralX makes my 2Ch CDs sound better than any of those "HD Audio" formats ever sounded.
I think the AVPs from Yamaha, Marantz, Anthem are great. If you must spend more money, then the Bryston and ATI AVPs would be great.