I do believe there is a considerable difference between receiver and integrated amp when it comes to sound quality. My friend has a 1000 dollar Yamaha receiver that he bought about 3 years ago and I can honestly say that its sound is not nearly as good as a budget integrated amp such as a Nad C320BEE. Most receivers have the typical glare and grain that is known of solid state.
If you still insist on buying a receiver, I would recommend either a used Arcam AVR100 or AVR200. Both are well below 1000 in the used market. If you like the sound a bit on the warm side, a Nad T762 would do. I believe the T762 is TAS receiver of choice in its price range and it is one of Nad newer model. You can get a new one for about a grand.
If you still insist on buying a receiver, I would recommend either a used Arcam AVR100 or AVR200. Both are well below 1000 in the used market. If you like the sound a bit on the warm side, a Nad T762 would do. I believe the T762 is TAS receiver of choice in its price range and it is one of Nad newer model. You can get a new one for about a grand.