Another dumb question

I was pleased with the improvement in quality I had noticed after adding a Bryston 4bst to my mains previously driven by the Yamaha DSP-a1's internal amps. The only drawback is that 4b seemed to require a higher volume setting on the Pre for the same spl as the DSP-a1.Then I borrowed a friends 4bst and bridged them for 800 watts per channel and the volume was less yet! This doesn't make sense. 800 vs 300 vs 110 watts? Hookups are rca and unbalanced was selected at amps. into Definitive tech bp10s. any help appreciated.
The input sensitivity of the amplifiers is different. Simply, the Bryston requires more input gain from the preamp to get them to "Go". The volume indicator on your preamp is a very poor measure of how loud your system is going to play, especially when swapping amps around that have different input sensitivities.
I had a similar experience when I replaced my 2 channel aragon with aragon palladiums, which are monoblocks, with my bk ref 20 in my theater set up... I believe that the preamp section of the processor your using is not strong enough to give the max gain to the amps... yes the power doubled so there should be noticable gain difference.. but if the preamp is not capable of the gain control you would need to "turn it up" higher to get the same volume in db as before... I dont know technically why, but that is my personal experience.
Good Luck!
It depends on what the gain value is for each amplifier.
Slartibartfast has the right point. Very often high powered amps require higher input voltage and so you should match the preamp for your new amp.
The info above regarding the input sensitivity of the power amp constitutes the majority of the answer to your question, but there is one other piece of information that may help you to understand what is going on. There is often a misconception about the "volume control" on the preamp. Volume controls don't actually "turn up" the volume, although that may seem to be the case. Actually, the volume control is an attenuator, which turns down the volume from its maximum output. If you were to remove the "volume control", the preamp would simply operate at maximum voltage output. Hence, the volume control actually decreases the voltage from the preamp's maximum full output.

In many preamps, the volume control is anything but linear. Many volume controls have a rather limited operating range, reaching close to their max output by the time the control knob is around 11:00 - 12:00. If your preamp volume knob must be turned beyond 12:00, it's really not a big deal -- it simply means that the volume control has a more usable "range" before reaching the point of lower attenuation.
No dumb questions ;just dumb answers. Sounds like a gain situation as descrbed above; good answers.
I think in many cases the input sensitivity of the amp needs to be almost 100 times that of the output sensitivity of the preamp for a good match. This varies however depending on the particular components and/or manufacturers being matched up. I've run into this same problem but only when trying to integrate a powered subwoofer. Good luck.
I'd buy a new system if I were you :^)
Sdcampbell is quite right. In general, the higher the position of the volume control knob, the less negative influence the attenuator will contribute to the sound. (The best potentiometer is no potentiometer.) However, there were/are a few old preamps still floating around out there that used the "pot" in the op-amp feedback-loop to actually increase or decrease the gain of the circuit, not as the typical in-line signal attenuator. Thankfully, not many attempted this as over time the circuit stability and sonic performance suffered. Gunbei- I think you're referring to amp input and pre-amp output impedance, not sensitivity. A ratio of 100:1 is an ideal. In practice, if cables are kept short, I've had good results down as low as 15:1.
Enjoy the music!
Thanks for the response. Is there an easy (read inexpensive) way to boost output voltage? A processor between the pre and amp for example?
Mostly all good answers. Bryston makes great stuff. If the VOLUME DIAL POSITION really bothers you. You can find a nice Bryston preamp USED at a fair price.
Most people have budgets to adhere to so price can be an issue. By having amp/preamp by the same mfg. these things usually are considered in the design.
Just remember it's the music that matters. If you're happy with your gear and the way it sounds, who cares what others think. Everyone has an opinion but remember that with your system only yours counts....IMO....... RAMOND
What effect would line voltage or amperage have on my situation? Since my system has been growing,I have been planning to run a dedicated 20 amp curcuit just for my amps. Almost everything is in an entertainment center and running through a single surge/ line wall receptacle of 15 amp curcuit. I've never had any problems or tripped breakers but this has got to be pushing the limit. the leds on the panamax appear to be fairly accurate as they always show when voltage is low at peak demand times (neighborhood). They do fluctuate durring high vol use, but never near danger zone.I've heard mention of folks seeing a marked improvement after switching to an upgrade power cord, so is it possible that the draw from so much at once is partly to blame?
Here is what is hooked up to one 15 amp curcuit
DSP a-1
sat receiver
fm tuner
sharp front proj.
Rotel 1080
Rotel 991
power sub 250wpc
And no, the house is not on fire (I checked)