Any Benefit to Bi-Amping Bookshelf Speakers?


I recently upgraded an old receiver (pre-HDMI old) to a Marantz SR7012 for an existing 5.1 system in the living room. Mostly just wanted to add functionality and get rid of all the legacy connectors but it sounds quite a bit improved as well. I added a zone 2 on the patio, but that still leaves me with 2 of the 9 amp channels without a home and the improvement so far has me wondering what might be possible. The wife won’t let me tear up the ceiling for Atmos until after we remodel the kitchen so don’t bother with that suggestion :). 

The front R & L speakers are B&W 685s2. Max power handling per the specs is 100W but they are bi-amp capable. Would there be any advantage to bi-amping a smallish bookshelf speaker like this with minimal power handling capability (the receiver already puts out >100W/channel) or would I only be risking blowing them up or messing up the integration with the center and surrounds by doubling down on power? I have the wires run through the walls for aesthetic reasons so I don’t want to bother pulling new wires if there’s not any expected benefit. Use is about 80/20 TV/Music so any benefits to 2-channel experience would be worth noting as well.

Thanks!
ethos123

It really depends on how the Marantz handles "bi-amping".  If the Marantz will send the same signal on both bi-amp outputs, then you should be fine with experimentation.  However, I have seen some receivers that handle bi-amp in a weird way.  They will use an active "comparator" circuit to determine the frequencies that the "bass" bi-amp output is actually using.  Then they will subtract those frequencies from the signal and output the "difference" on the high bi-amp output.  The result here is significant loss of sound quality.

In either way, I don't think you'll be getting much benefit because both bi-amp outputs will share the same power supply in your Marantz.  I have heard others that report an increase in sound quality.  If your speaker wire is all run through walls, then it may not be worth the effort.

Only if an active x-over is used to split the signal between low and high frequencies. One amp then gets only the low frequencies and the other amp the upper range signal. 
Agree unless you have an active x-over a total waste of time.
+1 on all comments above. Your B&W 685 S2 have passive crossover. Not worth it. Plus I would never bi-amp using an AV receiver. 
Thanks guys. I appreciate the info. Still a newbie and haven’t gone far enough down the rabbit hole to know the details about bi-amping other than that my speakers and receiver are capable of it. 

Guess I’ll have to go with plan B... speaker upgrade and an integrated amp for a hybrid system...eventually. For now I’ll just enjoy playing with the new toy.
+1 on your plan B. If you want to get better sound quality and better performance you should upgrade your speakers and get a good quality stereo integrated amp that has HT bypass feature for your stereo music playbacks and use your Marantz SR7012 av receiver for HT (surround sound movies).

You could upgrade to higher end series B&W such as the new 700 series S2 and these will be big improvements from your 685 S2. If you prefer a stand-mount or bookshelf speakers I highly recommend the 705 S2. They are the sweet spot in the entire B&W speaker line. The 705 S2 have the best price performance ratio in the entire B&W speaker lineup. They only retail for $2400/pair new without the stands but perform very well and come pretty close to that of the 805 D3 bookshelves except the 805 D3 cost $6k/pair new. The 805 D3 are better but not twice or three times better as the price suggested.

If you prefer floorstanders I highly recommend the 702 S2, which is the flagship of the 700 series S2. They retail for $4500/pair new. The new entire 700 series S2 do not use kevlar midrange drivers anymore and use a new material called continuum midrange drivers like the ones used in the 800 series D3 speakers. Both 800 series D3 and new 700 series S2 use the same method in decoupling their midrange drivers from the cabinets. Trickle down technology from the 800 series D3. Sonically the new 700 series S2 are close to that of the smaller 800 series D3 eg 804 D3 & 805 D3 but are priced much lower than the 804 D3 or 805 D3. Sonically the 702 S2 floorstanders come pretty close to that of the 804 D3 but are priced only half of that of the 804 D3 ($9k/pair).

You should have a listen to them. They share much of family resemblance in sonic qualities between the new 700 series S2 and the newer 800 series D3 speakers. They srounded more natural and organic than the previous B&W models, including your 685 S2. They don’t sound anything at all like those previous B&W models including your 685 S2.

If you upgrade to the new 700 series S2 speakers you will have to get their matching center channel speaker as well. If you go with the 702 S2 floorstanders you should get the matching B&W HTML71 S2 center speaker, which is the bigger center speaker for the 700 series S2.
If you go with the 705 S2 bookshelves you can get the smaller HTML72 S2 center speaker. It is very crucial that you get the matching center speaker with your main front LR speakers for timber match. It will also be most ideal if you can also get the matching surround speakers but not mandatory.

As for a stereo integrated amp choice I would recommend the following :

* Parasound Halo Integrated HINT6. Has HT bypass feature and has built-in DAC. So you can utilize its internal DAC. Has USB DAC inputs, spdif (coax digital), Toslinks (optical digital) as well as analog audio inputs. Highly recommended! It will sound good on the B&W 702 S2 or the 705 S2.

* Rotel RA-1592 stereo integrated amp. Has built-in DAC and same inputs as the Parasound HINT6 but the Rotel does not have a dedicated HT bypass input. However, you can configure one of its analog audio input as unity gain input for HT bypass. Just set the volume at 80 (out of 1 to 100) and save the setting for that particular input. So every time you select that input the volume will be disabled and fixed at 80. 80 is usually a reference level for unity gain setting. Unity gain is basically a HT bypass.
This Rotel RA-1592 will pair really well with the B&W 702 S2 or the 705 S2 if you decide to go with the B&W. Rotel and B&W always have great sonic synergy together. B&W, especially the 600 and 700 series, voiced and tuned their speakers using Rotel anplifications and electronics. They are meant to be paired together. But the Parasound Halo HINT6 will also sound great on the B&W 702 S2 or the 705 S2.

* Musical Fidelity M5si or M6si. They both have internal DAC and have USB DAC inputs. These are very refined and musical sounding integrateds. Not sure if these have HT bypass feature or not.

For HT ( surround movies) you can still use your Marantz SR7012 av receiver but if I were you I would upgrade to the new Marantz SR8012 flagship receiver. It performs better than your SR7012. Better bigger power supplies, better analog audio stages, better amp section, better DAC, better preamp processor section, better everything.
I appreciate all your thoughts and info on the B&W 700 series, integrated amps, and the 8012. Sadly, while I’ll inevitably wander down that “plan B” upgrade path eventually, I have a dedicated HT system in the basement and a 2-channel system in the bedroom that I get to make fewer compromises with in exchange for not tinkering too much with this one for the time being. Just because I’m a newbie with bi-amping doesn’t mean I’m totally green.

The living room system has to stay kid, pet, & wife friendly and remain unobtrusive with regards to the decor. Bookshelf speakers with grills pushed back into the built-in bookshelves, a SVS sub tucked away as best as such a beast can be, and in-walls for the rest. It sounds better than most peoples’ living rooms and impresses the friends and neighbors who don’t know what else they’re missing... but it’s never going to really be truly amazing without getting me into trouble.

I often dream of throwing the current timber matching out the window and putting some Devore Gibbon 3XLs, Harbeths, or something else really special into that terrible placement in the bookshelf along with an integrated amp just to see what they could do for the 25% time we use it for music...but then again, it’d be a shame to place those beauties into a box that doesn’t let them breathe. Something a bit closer to the 705s is probably a far more reasonable place to land on the cost/benefit spectrum given the constraints.
I see. I thought this is your only setup. 
It’s not the only, but it’s the first time my number of available amp channels didn’t match up with my number of speakers. Plus it’s the setup we actually use most and the one with the most reason to make concessions for style, practicality, & multi-purpose functionality since it’s the main living space... hard to fight the urge to tinker just a bit though :).  

Really do appreciate all the feedback and love hearing first hand accounts of good gear for down the road. Thanks again!