The Marantz manual says speaker cables with spades can be connected to the amplifier including a diagram that shows how. I checked the Marantz N30 amp at Best Buy and confirmed that spade lugs work. The speaker connection supports banana plugs, bare wire and spade lugs. When you loosen the screw, the spade lug connection appears at the bottom (YOU HAVE TO LOOK FOR THE SPACE TO INSERT THE SPADE).
The surprising thing is that Marantz Phone Support and an on-line retailer both said that speaker spades lugs were not supported. I eventually checked the manual and confirmed that Spade lug connector are supported. And, confirmed this at Best Buy on the amp.