Why is my amp requiring as much volume gain?

Just swapped out a pair of 1980 vintage Denon 1500 (150 watts stereo I beieve)in horizontal bi-amp configuration (using little XO crossover box).Know that amps have no mono conversion so it must have been horizontal (or no crossover would be neede as well).Two stereo amps combined in that fashion should be putting out 225 watts total correct?But then put in Bryston 4BST which is rated 250 and benches closer to 300 wats.But need to turn up my pre to 12 o'clock high to get what I'd get at 9 o'clock.Only thing I can think of is that the input sensitivity of the Bryston is much lower than the Denon's.But that much?Haven't tried to see if I really punch it but the Bryston SHOULD be louder or at least not require so much more of the dial.Guess if I do really turn them up (which I haven't yet)my guess is that in addition to sounding better harmonically (and no cut outs/crackling of course.Think Bryston is working as it should.They are as everybody say's prety indestructible)I expext it to be louder.But is the lower input sensitivity it?Why off so much versus less power and can I adjust it if I feel I am running out of dial room on my Mac 172 pre?
I think you've answered your own question re: input sensitivity. It is only really a problem if at max volume on the preamp you still don't have enough gain to satisfy your in-room max dB requirements.

One thing to keep in mind is that most preamp volume controls are more linear in the middle and upper control ranges and could possibly sound even better at the 12 o'clock position as opposed to the 9 o'clock position.
The difference in wattage output translates to less than 3dB in added volume potential. That's only a little bit louder at full volume. It's just not a dramatic difference.
The Bryston amp has an input sensitivity switch that selects 1v or 2v input voltage. Check with the owners' manual or Bryston to see if you're using the correct setting.
I once owned a Bryston 4B and noticed exactly what you mention, but maybe not to the same degree. I did have to turn up the volume knob a little more than with any of my other amps to get the same perceived loudness. But no matter the volume, that Bryston had the best, most controlled bass I've ever had in my system. When talking with Gilbert Yeung of Blue Circle and Mike Farnsworth of Talon Audio a few years ago at CES, both commented on how well Bryston amps do bass.
Thanks guys.I might check to see where the seting is for 1 or 2Mv and yess were not talking about going from a 50 to a 300 watt.Notice the newer maggies eat it up even more than before (went for III to 3.6) and they have always been hungry.Might at some point slap another Brsyton on.And Gunbei I will agree that the bass is nice with Bryston but I sold Krell for about 6 years and when I heard other amps we sold (Mac,Adcom etc-small shop) or in the field where I heard other gear saw or rather heard why so many speaker manufaturers used krell for demo'ing there speakers.Nothing else (Class or A/B)had the "grip" if not quantity of the Krell.Now that came part and parcell with a decent if brite high end (was told by freinds and amaggie krell was bad match since they had such stong resolution) an a metalic midrange I found clinical and etched.Fatiguing and not a good match for a Thiel defintely.Well I have a KSA300S I picked up froma a former customer but toild my buiddy (it's his maggie system actaully) that he should save money and not buy my amp so I found him Bryton which has (and this is general oppinionm) much better chromatics thrughout the frequency range.Yes good amps at a good price built to last.There is beter but you have to pay through nose (Levenson comes to mind here).Me I'd like to hear all the brew ha ha about the new John Curl Parasopund JC1 400 wat amp.Reviews I always take with a grain of salt but noticed more than one reviewer bought his review smaple and that makes me sit up and take notice.Not cheap at $K but think it may develope a Plinius like cult following given first few years reaction.
dont worry were your volume is all equip has different sesitivities
Just to put this up if anybody does a search for same subject contrary to what GS 5556 mentioned the 4 BST does not have an adjusrable input sensitvity switch.It i permanetly set at 2Mv so coresponinding pre must be set up at a higher point that the Denon wjhich may have been at unity gain at say .7MV.Haven't gone to hear system at buddies but he say's most music sounds better especially in harmonics and I need to see if if truly high volujme is can be achieved with out overdriving pre but again it may just be a psychological thing with where the volume has to be.Owner has claimed that some muisc like and old Lee Morgan recording sounded tyerrible as if the trumpet where being played in another room (the bathroom) and not with the band.But you can't judge a system change with one bad recording especially since overall assesement is thumn\bs up.Will pot one more to see if there are anb problems.Maybe I thoughld chenge it from bi-wire to single wire set and that would help though this is counterintuitive.
Baclk in the 80's when Denon made the 1500 amps standards had not been established or standardized the way they are today.Back in the 70's it got so bad the fed's through the FTC had to get involved because of course a particular spec can be "hyped" when not taken into a level playing field with others.Thus you had "1000 watt" car ampos that sold for $29.99 but were no more powerful,and delivered no more cvurent than another manufaturer being more honest who might sell a 100 watt amp that sounded no less lod than the "1000 wat monster".This of course takes place today when say s sub manufacturer claims "20-20Khrz +/- say 15 db".Most reputable manufacturers will either stick to +/-2 or 3 db and give perhaps another spec at +/- 9db.
The issue now is that bnack in tha day it may have made sense to have pre's with "hot" outputs or input sensitivity because even with phono sections voltage output sources were lower with LP's.But the advent of CD's led to line level to go to a higher level from say 1.5 to 5 Mv.Thus THX (*which the Bryston is certifed as) m,eets the THX 2MV input senstivity.BTW went over to system and after hearing his old MGIII's that sounded "Ok" with the DFenons the 3.6's sounded like shit.Now harmonically,soundtsage every perameter they sound great anmd I realize why Maggies are considered by many to be the best value in audiophile speakers/Yes they won't reproduce aricraft engines taking off (as they suck down their unquenchable thirst for current)in terms of volume and yes they lack deep (last octave or two) of bass they deliver the goods.Now with the Brystons (or I imagine a good AR VT100 or pair of Hurricaines) they sound great and revela losy recodings where as the old set up just masked the glory and the gory.Makes you want to invest in better digital (maybe leave the Proceed as a transport and get 24/96 upsampling D to A),compare the phono in the Mac 712 to another,and even for this wire skeptic give some good matched wires with a high cost to value ratio (Kimber?Cardas-nah too soft good fopr softening Krell nastinties,and even with Cats compare Mappleshade to Omega Mikro's etc).Anybody who has any suggestions and is reading this other than a pair of REL or vandersteen FAST multiple small driver subs than can blend which is the nect step I am all ears.
plenty of gain.It was just in his head about volume position.Distortion lights came on at 4 o'clock but between 2 and 3 o'clock was ear bleed level.But just because I know that they eventually did light up wonder if it was pre distorting or amp making me wonder what the Mono's or 14's would sound like.But again there are limits of speakers at a certain point where Maggies just won't blow the roof off.But it was a psych issue and PLENTY loud,ear bleed level if he wants.
But now it shows which CD's like great sounding 20 Bit K2 or the best XRCD,Mappleshade,and the creme de la creme Venus "24 bit hyper magnum sound" (availible on LP but because of duynamic range check out the 4 ballad LP's Archie Shepp did with same group like "True Blue and True Romance".And now the Rudy Van Gelder Blue Notes really sound like they were recoded in his parents living room (wjhich they were) so this amp.speaker combo shows the sonic limitations of all those Prestige and Blue Note CD's though the latets RVG series BN's amd K2 20 Bit Prestige (and Creedence Clearwater don't forget which were on Fantasy one of the few non-jazz and Blues acts in thier catalogue"Classic Lp's are best but latets K2 20 bits sound very good as I found while selling jazz CD's as well as Krell,Mac,B&W etc for 6 or 7 years ago and they just got good before I left 4 years ago.)Took until about year 2000 for Engineers to figured how to master CD's.The early ones now sound dreadfull.

BTW Q: "What's the difference between a Blue Note and a Prestige recording?A: "Four days or practice"Old joke but so true.Try most JVC XRC's.Mapleshades Clifford Jordans "Live At Ethells".Great performance recorded with modified mikes,thier own wires DIRECT to to track digital tape.No board i.e. EQ,Compression,filtering etc.SDeems like to many engineers want to be the 5th Beatle and Mappleshade it's crystal clear.Only bested by the fantastic Venus recoding from Japan.Great Shepp.Eric Alexandera few re-issues of HQ 70's recodings by masters like Al Haig but a whole roster of great keyboard player and better than ECM or any other recodiungs you can compare.Try titles i reccomend you won't be sorry and get back in touch.I have about 3K jazz CD;'s and same number of Lp's and know my 49-69 era very well.