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
if you're otherwise happy with your system i would simply add a two channel amp through the front preouts of your avr--this should give you better quality amplification for stereo listening. something like parasound would be a good match.
If 2-channel is important to you I think an integrated amp with a HT bypass is an optimal solution. Neither the preamp nor amp sections from your AVR are doing you any favors, so an integrated elegantly solves both issues in one box. I'd recommend a Hegel H160 as it has a HT bypass, is a big improvement for stereo over your Marantz and has the juice to power your B&Ws, and there are a few available now for around $1500, which is less than half of retail.

It sounds like there could be a settings issue possibly affecting your stereo performance. Regardless, the H160 will bring your 2-channel performance to an entirely different level while still allowing you to use the Marantz for sourround processing and amplifying the rear channels. BTW, with this setup the Marantz is completely out of the playback chain for stereo listening, and you can switch between stereo and surround with the push of one button -- in case you're not familiar with the HT bypass function. Anyway, hope this helps and best of luck.
@loomisjohnson - he is having a gain level problem when using his AVR for a normal 2-channel analog preamp.  An outboard external amplifier would not really help him.  And it would be better just to get an intregrated for 2-channel preamp/amp and use that as HT Bypass when he wants to watch movies.

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The Hegel is definitely a high resolution conventional Class AB "neutral" sound design.  Or you could look at something like Krell Digital Vangaurd integrated for a more creamy/liquid "Class A" sound.   These are very nice as well, but it really depends what kind of sound you're looking for. 
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