What's output of 4BST convereted to mono?

What's beter using two 4BST's or 7BST rated at 500 (bench cloder I think to 600) or goiing wiht stereo 14BST if one is after mopst watts per dollars?Also anyone know where one can get to sensitivity swich and this something a consumer should try and find and change?Where is switch and is it it easy to switch to higher imput sensitivity if it is factory or user set at lower number?Any signal degredation i.e more distortion overall if one is using pre-amp anod source which I think fall into standard ouptut voltage ranges (a Mac 712 pre-amp fed by a Proceed player/DAC.
Original published specs from Bryston identify the 4B ST rated at 250 watts/channel stereo @ 8 ohms, 400 @ 4 ohms, and 800 @ 8 ohms bridged to mono. The 7B ST monobloc was rated at 500 watts/channel @ 8 ohms and 800 @ 4 ohms.
I think the sensitivity switch is a simple mod to the 4BST that can you can have done by Bryston - mine has it; two pot screws on the front to adjust sensitivity level.

I would go for two mono 4BST if you really need that much power...they are easier to find second hand.
Got it for buddy of mine to replace 20 years old Denon 150 watts on Maggie III's run latterally (not mono conversion switch and had little XLO1 x-over.Now 3.6 's needed more power and one Denon had intermitent short.I explained that since it was lateral bi-amping to my buddy that two 150 summed to 225 watts (unlike bertical if each amp could have ben converted ajnd would have mostlikely put out twice power ormore).So Bryston is rated 250 but know tey bench close to 300.Yet because of what must be different input sensitivity my freind is all weirded out that he has to turn it up tp 12 o'clock high to get it to what (even with 3.6's) he got at 9 o'clock.But I told Bryston HAS to have more mpower.Anothjer post informed me that many pre';s even work better at 12 o'clock or bit higher than kept low.But freind has yet to say he does not have enough voluime if he goes to 3 o'clock say.Think maybne he should buy another (and without saying is nervous that it isn't as loud evenm though he has yet to bury it).IHe said harmonics are much better but maybe he should have gotten 7's or 14 but if he wants power (and Maggies can suck current) two 4BST's are way to go.Just upset that he is so hung up even though i told him that it is do to lower input sensitivity nd having it switched to lower setting (as long as he can get enough uice when he needs it) may mean that lower input sensitivity could prevent greater disortiuon when set lower.But still he is hung up that it does not go at 9 o'clock and now that volume requires 1 o'clock.Just neurotic BS.He was allset to buy an inaproppriante krell at twice the price before i told hom this combnop was about the most poular one their was for maggie owners plus warrant was a plus.He whinned that his Denon ws cutting out even though he bough it in 1982!!!!Man now I know why I am more relazxed then the 6 years I spent selling Hifi.Some pople just want to worry!
Thanks I'll try to find sensitivity swith and flip it if I can or send it in.I just think a good fast REL (or pair of fast pitch accurate subs) would be where I would want to put money before and amp I wasn't even sure I needed.