Musical Sound Quality of AV Surround receiver vs. pure Stereo


Running Linn LP12 turntable, Bluepoint No2 stylus, with Jasmine phono pre-amp, Marantz sr5008 with B&W 685s2 on LR fronts with 686 S2 LR surround,  Paradigm CINEMASUB Cinema Sub 300W Speaker.

3 questions; 1) While I canceled out the center channel (using Marantz Audyssey setup), I am playing 99% from my turntable and CD player (Yamaha w/ DAC built in). The depth and spacial separation of the music is uncanny, but difficult to phase given it is being played in a digital (Music setting) format from one of the settings on the Marantz receiver. When I switch to pure stereo, the volume has to be turned up and the depth of the soundstage just isn't there. Would upgrading to a more powerful and musical integrated amplifier help (i.e. Anthem  Anthem MRX  720?) help with its killer room correction or 2) Do I look for a 2.1 integrated amp or tube amp to compliment my B&W 685S2's and sell the 686's or 3) do I just bite the bullet, look at a traditional good integrated amp or tube amp for around $3K with $3K Audio note AN-K speakers. Traditional sound....

Thanks, I am new to this group and have read a number of discussion threads. Obviously, a lot of you are infinitely more knowledgeable than I am, so any and all replies would be greatly appreciated. PS No man cave, this system is in my living room, so the wife is a little particular about too much gear ! Thanks everyone.
128x128phill55
aux, you may very well be correct--could be gain or could be the inboard amps not be being up to snuff--his speakers may be relatively hard to drive. an integrated with ht bypass is defintely a good fix, but not necessarily the cheapest.
Thank you all for taking the time to lend me your advise. My impression is, if connecting the Marantz to my TV is not a priority, I really am better off trading in the Marantz and the pair of B&W 686 S2's for a nice integrated amp to drive the B&W 685's.  However, would a Outlaw Audio RR 2160  which is 2.1 have enough power to drive both speakers and the sub woofer. I like the complimentary bass / fullness of the sub to help drive full spectrum of the sound of my vinyl.  If not an Outlaw, 1) what would you recommend? 2) Or again, trade in the B&W's for a more robust Audionote AN-K speakers. Thank you for any comments or suggestions
The sub looks to be self powered so no concern there.  The first question you need to answer is if you like the 685s enough to keep them.  If yes, then almost any decent integrated stereo amp should yield a significant improvement over your AVR.  The Outlaw should work fine and is a good amp for the money, but it's not up to the standards of the Hegel IMHO (or probably the Krell either, but I'm not familiar with that unit). 

If you're upgrading the speakers, wait until you figure out which ones before upgrading your amp so you make sure they work well together.  A lot of people like Audio Note speakers, but they're quite different from B&Ws and there are lots of other great options out there.  Hope this didn't just confuse things further. 
Is the Hegal an iij integrated amp which CNN accepts a powered sub woofer? Thanks,