Spade lug connector to Marantz amp

These should do the trick!

or these

https://www.audioadvisor.com/prodinfo.asp?number=CRCAB&gclid=Cj0KCQjworiXBhDJARIsAMuzAuweLmiEMvpL7RpuiLIZzlFr_qfa1ITg-_sdZqSlRY5AW7CMRPLdVZ0aAhMaEALw_wcB

or these

https://www.transparentcable.com/products/transparent-spade-to-banana-adapter?variant=24753250369600&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=Cj0KCQjworiXBhDJARIsAMuzAuwIzLWT87gART8Coe7HN4cmCUXkX6fSmSNml7Kr9a1Ob-rtwKMmRf0aAklZEALw_wcB

Those plastic shrouds are a PITA when it comes to spades. My Marantz PM15S2 had them and only one size spade would fit in it and I could never get a proper bite on it. My solution was to send my cables back to Zu Audio who reterminated them with bananas for $10/each. I don't know why they or anyone still uses them.

All the best,
Nonoise

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.  

Marantz Manual for Speaker connections

Well, if you can't get it to work, th two guys above gave you a good solution.

FYI,  I honestly think bananas are better.  Too many connectors and spades are made too hard to grip well under pressure.  The exception are WBT's with built in springs.

Otherwise, bananas are always more reliable.