The Oppo is great, the speakers are nice, the Marantz is a good buy...but aren't you selling yourself short? For what you can get out of the Marantz, you should save on the Oppo and go for the 103, I doubt you will see or hear a difference.
On another note, Marantz does NOT rate the power on the 6007 below 6 ohms. Your speakers are 4 ohms. You just might cook your receiver? I'd get a guarantee in writing from someone.
My suggestion is a preamp and amp combo. You need a power amp that can handle that load. If your budget is stuck at $1750 and you need all of the features of the Marantz, consider it as a pre/pro only. Or look at an Emotiva UMC200 or Outlaw, $650 approx. Buy the Oppo 103 for $500. Blow the rest on the best used amp you can muster up from Audiogon. There's amps from B&K, Anthem, Sherbourn, Adcom and many more in the $500 range that can make your speakers sing. Also, your receiver could probably handle the load on the rear speakers. Now you only need 3 channels.
On another note, Marantz does NOT rate the power on the 6007 below 6 ohms. Your speakers are 4 ohms. You just might cook your receiver? I'd get a guarantee in writing from someone.
My suggestion is a preamp and amp combo. You need a power amp that can handle that load. If your budget is stuck at $1750 and you need all of the features of the Marantz, consider it as a pre/pro only. Or look at an Emotiva UMC200 or Outlaw, $650 approx. Buy the Oppo 103 for $500. Blow the rest on the best used amp you can muster up from Audiogon. There's amps from B&K, Anthem, Sherbourn, Adcom and many more in the $500 range that can make your speakers sing. Also, your receiver could probably handle the load on the rear speakers. Now you only need 3 channels.