long answer, very opinionated
What is "needed", and what is "wanted" are not always the same things.
Keep in mind, everybody had a "humble opinion"
Here is mine....
Your tastes in music:movie can be a huge factor in the quality of the system that you may want or need.
Many people on this site are movie driven, with fewer of us more inclined for music rather than movies.
The equipment that movie people choose tends to have a greater emphasis on video processing, as well as processing the audio into several, or even many, different speakers. The Marantz reciever is perfect for highend movie applications.
Pure musical needs tend to be best handled with a simple stereo preamp & amp combination, or a stereo receiver. In this case, the Marantz, with all of its video/audio processing, would be overkill.
If I was building a pure musical system, I would place as much as 70% of the money into a single pair of main speakers, with less emphasis on the electronics.
Building a movie system, the main speakers are of less importance (the center channel can be more important), and the speaker budget must be spread over more speakers, AND a portion of the budget must be allocated to the audio/video preamp features. General recommendations place the percentage of the budget at 50% for the speakers, and the balance in the electronics.
Your room size is pretty good, such that bass output from bookshelf or small floor standing speakers would be most likely inadaquate for musical needs.
Some people recommend the use of small bookshelf speakers combined with a sub for music.
I personally don't like the bookshelf/sub combo for music. Depending upon the recording and the frequency of the bass material, the mono sub may lack the stereo effect to give a full and pleasant sound.
I would look for a floor standing speaker that could handle the bass output of classical music without needing a supplemental sub.
That all said, the B&W FPM series of speakers were designed for movie application, especially in combination with a plasma or LCD screen. They are pretty, will perform well for movies, but will leave something to desire for music as the main speakers are not going to carry the musical needs by themshelves unless accompanied by the sub.
There are other B&W speakers, such as the 700 & 800 series that I would recommend, that will handle both music and movie needs, though at higher cost.
Deciding how much to spend on speakers is a personal issue. There are other speakers on the market that can compete with the FPM or 700 & 800 series B&W speakers, many times at a lower price. But at a lower price, build quality, something that B&W is reknown for, can be sacrificed. Then again, the FPM's are WAF (wife acceptace factor) friendly.
I cant say anything negative about the Marantz equipment, it seems to be a well built, nearly a flagship model, from a traditionally well recommended brand of audio equipment. It is a serious home theater receiver and could be well worth the money.
Can a slightly less expensive unit from Denon (such as the AVR 3805) or Yamaha do as good? Maybe. But I must say, the Marantz just plain and simple looks GOOOD.
Reference the HDMI/DVI, what kind of TV are you using with the system? If your TV lacks the inputs, obviously the outputs would be a waste. Do you need the bells and whistles that the Marantz is going to provide? A lot of people are using less expensive equipment, are quite happy with their systems
Shifting the allocation of your money could achieve a better system.
I would start with speakers.
Good luck, and fun listening
