Syed, welcome. Yes, as Rick said, you have to make your own decision as to which features are most important to you. You might also note that the 605 has a simplified version of the Audyssey automatic calibration and room equalization system(the 2EQ), which many believe has an edge over the system in the 661. The basic amplification capabilities of the two are quite similar and shouldn't be a basis for your decision.

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Enjoy the music, not the equipment.