Hi Tathata, if you are new to audiophile systems that is one hell of a speaker you have there. As you have discovered, speakers like the 802D are very demanding on amps. Anything less and it will show up the amp mercilessly.
Unfortunately it looks as if you have gone for 5 speakers, so the salesman is correct with his recommendation for a quality 5 channel amp setup. If you wanted to save money, you could sell the rear speakers and center channel speaker and spend the money on buying the best amp you can get for your 802D's, which are superb speakers. The classic match for B&W speakers are Classe amps - not cheap, but you may be able to find some in the Classifieds.
Good luck.
Unfortunately it looks as if you have gone for 5 speakers, so the salesman is correct with his recommendation for a quality 5 channel amp setup. If you wanted to save money, you could sell the rear speakers and center channel speaker and spend the money on buying the best amp you can get for your 802D's, which are superb speakers. The classic match for B&W speakers are Classe amps - not cheap, but you may be able to find some in the Classifieds.
Good luck.