Bi-Amping Options B&W 801 Series 2

@russ69 A single MC-252 got better highs and better lows than the Rogue Stereo 100 from the Warfedales, in my opinion. I had issues with very dissonant distortion from an Electric Light Orchestra recording when running both the Freya and the Stereo 100, although the main issue was with my cartridge & Numark turntable & arm, as I recall.  Taking the Freya out of tube mode removed the distortion. I actually came to prefer the buffered mode for the Freya. 
The B&W have a lot more top end than my vintage Warfedales, ARs, and KLH models, so I was thinking that with the B&W speaker, I wouldn’t mind a bit of roll-off on the top end. 

@raysmtb1 I am using at least one tone control now, the ‘Environmental’ equalizer McIntosh MQ-107, and although I haven’t attempted to ‘curve’ it as yet, I am boosting the bass at ‘2’ out of 5 or 6 (I can’t recall exactly), but I’ve had to turn it down from ‘rattling the windows’ on some recordings. I would say you’re correct, although you can hear the bass without the EQ boost, you can hear it a lot better with it. 
More to your point, I’m not sure what more power will do for me. The manufacturer describes the bass driver as “12 inch (300mm) high-power polymer-cone woofer,” and I have read comments about what a nice speaker it is (was), but that it required a lot of power. When I have it turned up to ‘loud’ I’m 21 dB consuming about 25 Watts. But the amp experts always talk about having enough reserve in either the choke or the capacitor bank to deliver high amounts of current in a short amount of time to properly deliver the ‘transients’ that make for dynamic playback. 
But I think the also say that twice the power takes ten times the Watts, so . . . how much is enough, and how much is too much? That’s kind of my question. 

@tomcarr I like the way you think. I’m probably goin to try it, regardless, but I thought I would ask the question here, to gain knowledge from experts and those more experienced than myself. I’ve got a good deal of money tied up in the system at this point, so there isn’t a lot of room for ‘playing around’ in ways that failures go in the trash can. Ben there, done that, got the T-shirt and a few damaged amps and speakers to prove it. :-)

@lowrider57 Thanks for the compliment on my system, I’ve certainly been all-in since COVID struck which coincided with my retirement and my wife’s death May she rest in peace. 
Regarding the crossover, the speaker comes with two sets of speaker terminals, so that to drive them from a single amp, I would need strap the two positive terminals together and strap the two negative terminals together as well so that the power from the two wires could get to all four terminals and from there to all three drivers. 
It is my understanding that each original set of speaker terminals were connected to their own crossover network, and the drivers receive their signal from the crossover network internal to each speaker, but external to the amplifier. I include a picture of the crossover networks in my virtual system photos. Both crossovers inhabit the same circuit board, so it is difficult to distinguish them. 
I can definitely vouch for the fact that if I turn the one amp off driving the midrange and tweeter, all I hear is muffled bass notes, not at all distinct or loud; likewise, if I turn the amp feeding the bass drivers, all I hear is faint ‘tinny’ treble, again, not very distinct or loud. But when both amps are turned on I hear much more than the sun of the separate parts, the notes are clear, distinct, and loud, there is a sound stage (speakers disappear) instruments are well-placed within it, and there is plenty of ‘air’ around the instruments. As one listener noted, “I feel as if the musicians are in the room with me.” It is truly astonishing, and I didn’t have that kind of sound until I brought the B&W 801 speakers into the mix. They are truly a magnificent speaker: what you have (in the recording) is what you hear, no doubt. 

@xenolith Let me assure you, I am enjoying my new (to me) speakers. I bought the speakers used from a dealer in northern New Jersey. I won’t give their name because previous posts on this forum that referenced them were removed silently. Suffice to say that they would have been perfectly capable of replacing the original, if what I have is not original. I have seen some crossovers on eBay that are much heftier than mine, but I think I will hold what I’ve got for now.
I find your configuration interesting. I haven’t, as yet gone the mono-block route, I was already on the dual-mono path before I found out about it.
Your knowledge of this speaker ‘system’ (it’s really more than just a speaker, isn’t it?) far exceeds mine, but you seem to know what you’re talking about, and I like what I hear about it being easy to drive. The original designer, from accounts I’ve read was trying to correct the ‘muddy’ bass of the original series by going with a an intentionally stiffer material for the cone. The function of the optional bass alignment filter was to boost the signal to the bass and ‘wake it up’ as it were, as well as provide 6th order Butterworth filtering. Most people were happy with speaker as it was. B&W also offered 11” stands for them, but again the original designer said that was just to lift them up over furniture found in a typical recording studio, they weren’t necessary for use in the home.
Anyway, as I said, I’m enjoying them, and I’ll try driving them with the Rogue Stereo 100 and see what I think.

Thanks for the response, and that goes to everyone who has responded thus far. I really appreciate it.

@xenolith Thank you. I just hooked up the Rogue Stereo 100 to the ‘High Frequency’ taps and the sound is so sweet. I prepared a long post to update everyone on this thread, but lost it all on an errant finger click trying to preview it. Oh well. The 2nd MC252 has Ben removed from the temporary system downstairs to drive the McIntosh XRT20s that are being installed on the ‘New System’ upstairs. If the XRT20’s need another MC252 to get off the ground they’ll get it. Testing the XRT20‘s revealed that they need a lot of juice to move the woofers; haven’t hooked up the tweeters yet: we’ll see. Again, thanks for the sympathy and advice. 

@lowrider57 Thank you for the kind words. As best I can tell, the crossovers are, and always have been separate. From the response I’m getting on this thread they may well not be stock. In any case there are others for sale, so I’m not as worried about the ‘Bass Alignment’ option as I once was. The bass is powerful and clean without any additional equalization. Thank you for your concern. 

@tomcarr I’ve never seen an impedance curve for the 801 S2, but I checked the user manual specs and found that while they are rated at ‘Nominal 8 Ohms’ in parantheses immediately following it reads “not falling below 4 Ohms.” I expect the drooping impedance would most likely occur in the lower frequencies. I think I’ll try the MC252 taps for the low frequencies over from 8 to 4 Ohms. 
I also checked the specs on the MC252. Since it has autoformers, it can deliver max power however you hook it up: 250 Watts in stereo and 500 Watts in mono continuous sine wave with up to peaks of 50 Amps to each speaker. We’re I to go back to using both MC252s on the B&Ws I could run them either bridged or parallel into 4 Ohms. The parallel configuration would deliver the most current, I would think. One day I may try it, but after lugging that 96 lb. beast upstairs yesterday, it’s not going back down for a while. It seems perfectly suited to drive the XRT20s. 
 

@erik_squires Point taken on using identical amps as monoblocks. To be honest I was a bit intimidated at the prospect, I was afraid I might blow something up. But there is plenty of protection built into the McIntosh amps. I may try to source an MC2255 for the XRT20s and move the MC252 back downstairs for the B&Ws, or possibly bring the 65 lb. Rogue upstairs for the XRT20s, although the XRT20s could bring the Rogue 100 into clipping, and does NOT have the protection the McIntosh units provide. I think my current configuration makes the best use of the power I have available.