frequency response - B&W vs. Monitor Audio

I currently have a pair of B&W 685s and I am considering replacing them with a pair of Monitor Audio BR2s. The MAs freq resp gets down to 42Hz; the B&Ws only get down to 49Hz. Is this an audible difference? I would be getting the MAs through a friend who has access to wholesale prices and I will not be able to audition the MAs.
2nd issue - I am considering high-passing my bookshelfs through an active crossover in a powered sub. This will cut out frequencies below 80Hz before the signal gets to the amp and the bookshelfs. If I do this, does it matter if I upgrade to the MAs? Their high end is 30kHz, the B&Ws high end is only 22kHz. Thanks.
If you have access to wholesale prices you owe it to yourself to look at the Platinum series. They perform way above there pay grade.
"The MAs freq resp gets down to 42Hz; the B&Ws only get down to 49Hz. Is this an audible difference?"

Those are only numbers, its how they sound that counts. Besides there is very little music below 50hz.

Bob says...Those are only numbers, its how they sound that counts. Besides there is very little music below 50hz.

I agree with the first sentence.The pitch of the sound is what makes or breaks it.
I disagree with the second sentence to a certain extent.While there may not be a lot of music below 50Hz,what's there is important.The lowest registers of the piano and organ,pipe organs,tubas,etc. fall in this range.Again,the pitch of the sound is very important.Of course these are just my opinions and everyone is entitled to their own.
Also, regarding the high end frequencies, very few folks can hear even up to 20kHz, as far as I know.
Don't forget the room and setup!
Also, when it comes to LF extension of above named, I see no tolerance and certainly no ref to quality of sound.
Two points: everyone is right, frequency response, in and of itself tells little about the "sound" of the speaker. Second, response above and below what we can "hear" influences out perception of the sound that is audible to us. I find that my subs make music sound more realistic even when there is supposedly no content present in the range they cover. The human perception system is fascinatingly complex and not yet completely understood. There was a recent experiment in which it appears that our sensitivity to ultra high frequency sound was not through our ears but through the body in some way. This sounds weird and it is but when the body was blocked from the sound and the ears left exposed the sound could not be perceived; when the ears were blocked and the body left exposed it could. As Haldane said'"The world is not stranger than we imagine, it is stranger than we can imagine".
The lowest note on a standard piano is A1 @27.5hz, and if you double that to 55hz that is the next A up (A2), you IMHO
are missing a lot of musical sounds from below 50hz ie some low notes on a bass guitar,synths,organs etc and that last octave again IMHO is vitally important for depth, unless of course you only listen to the Triangle, Flute or solo Violin music.
The 'demo' disc that came with my sub has an organ track with a 16 2/3 hz pedal tone.
The Saint-Saens Symphony #3 with Organ is awesome.
It'll rattle everything in house. You can see the warble in window reflections.

I believe the Bosendorf Imperial Grand goes 1 octave below A1. This instrument has 97 keys, not 88.

Magfan you are indeed correct, the Bosendorfer mental amount of $$$ Imperial (best piano on the world by a long stretch)goes down to C (additional 9 notes) to give a full 8 octaves, so A below A1 (if there was one) would have a Hz of 13.75 add a few (can't remember the multiplyer to give a semi-tone increase (been a long time since I was at musical instrument technology college), and it is still
rather lowdown Hz wise.I've only ever played on the Bosendorfer 7'+? model daily (way back), what an instrument that was! Having only tuned piano's (back in the day also) with the Standard A1 27.5hz(that is/was hard enough to do) the big fella must be a piano tuners nightmare all those additional notes in the bass, if you have a cold, forget it pack up your tuning crank, go home, you ain't gonna hear the 'beats' that low.
Thanks for all the posts, very interesting. My amp is a 15 year old Yamaha RX-485, I'm also running a 15 year old Yamaha CDP. I cannot decide if I want to upgrade the speakers or the electronics! Budget is about $1600.
No one has mentioned anything about high-passing the B&Ws, would that help? I'm afraid it would hurt the imaging of the sound, too much coming from the sub in the corner.
Even if I upgrade the speakers, I will still be missing that extra low-end oomph; I think I need a sub woofer.
I will probably purchase a <$1000 integrated and mate it with a sub woofer. The room is small, like 14x12x8. Possible combos include Cambridge Audio 650 + SVS PB10, or an NAD C326 with a Velodyne DEQ-10R. NAD to sub connections are quirky. The CA has A/B switching, so I can do a high-level connect to the sub.
If you're getting a powered sub, then it does not matter whatsoever whether your bookshelves go down to 42Hz or 49Hz. More important is how the speakers perform to your liking, in any case.

As for the high frequencies, it's really irrelevant whether a speaker goes up to 22kHz or 30kHz since human hearing maxes out at 20kHz, and for most individuals, much lower. So unless you're playing SACDs of dog whistles for your pet's enjoyment, this is also a non-issue.

Get the MAs if you like them better than the 685s, but not because how high and low you think they can reach, especially in this case.
The MA BR line is their entry line and IMO inferior to the B&W 685s you arleady own. If you like the MA sound, I would consider the new MA RX2. These have an 8 inch woofer in a bookshelf cabinet and they rock. Really high value for money. Also, they would be fanstastic with a NAD C326. The Cambridge stuff will probably be too bright with MA speakers. NAD is a much better choice.
Jaxwired your point is well taken regarding the BR2s, and if I had done my homework before buying the B&Ws I may well have ended up with the MA RX2s.
I think I am going to buy the powered sub and upgrade my amp as well; with a powered sub, would the CA still seem as bright? I like the CA's dual speaker channels, enables me to purchase new speakers (B&W 683 or better) later and basically have a 4.1 system, on my way to building the perfect 5.1 surround system for the living room.
Also, the CA 650 has 25 more watts than the NAD, but it does not have main-amp-in connections. Still no one has posted regarding the idea of high-passing the 685s - good idea or not?
Post removed 
Post removed 
Dylanhenry-, there must be a reason why speakers (tweeters) go way beyond the human ear for defining a positive musical note and ampfliers to take the Musical Fidelity amp the 'Titan'(just as an example as I sure all amps go way beyond 20khz) can hit nearly 100khz, now the human ear because we do not have the hearing of a dolphin, or even an elephant, we hear very high khz 'Harmonics' way above 20khz, which is what every musical note has, which is and I quote;

'Any of a series of musical tones whose frequencies are integral multiples of the frequency of a fundamental tone'.

So although one may hit the middle C key on a piano we actually hear the harmonics of that note way up into the stratosphere of khz.How high up? who knows?

Apols to the OP, sorry my posts are off your subject.
i have to agree with the guy who said MA BR is inferior to B&W 685's.. i've heard both and the 685's sound much fuller/musical
Gawdbless, yes there is a reason why tweeters can perform beyond the range of human hearing and that reason is called "marketing" ;)
Bob_Reynolds, thanks again for another interesting equipment suggestion, will research it in the near future. Regarding surround sound, I won't be able to place a system in the living room for about a decade - kids are too young. So I was thinking about starting to build up the speakers - B&W 600 series looks very nice.
I am going to stick with the 685s and definitely get a powered sub. Amp is TBD.
Thanks all...
I have all new electronics in the listening room, and I am currently "borrowing" the 685s from my upstairs home theater. I want the 685s back up there, so I am now considering Monitor Audio BX5s, PSB T45-T55...listening room now features a newer Denon changer, the Halo P3, and a 200wpc Rotel amp...
went with the MA BX5s and I'm very happy with them...