Thanks for your suggestions. Regarding the audition with an integrated amp, my first objective was to see how the speakers sound to my ears. Yes, I understand that using an integrated amp vs AV receiver is a different ball game. At the same time, I wanted to pick the bookshelf speakers which suits my ears. It was in that context I could find PSB Image B6 to my liking.
The second thing is I also used Marantz SR6006 for auditioning the speakers. Of course it was good and I could still see B6 speakers sounding good to my ears. Yes, I also take your point that I cannot blindly assume that the NAD receiver will sound the same as the integrated amp.
Coming to the speakers budget and AVR price ratio mismatch, even prosenjit advised me the same. My idea is to upgrade to towers some time down the line. So I have taken a small step in that direction. Having said that, when I auditioned both Image B6 and DC6, they were sounding great and I couldn't believe that the sound was coming from bookshelf speakers. I am planning to audition other bookshelf speakers as well.
