I think you are confusing input voltage sensitivity with voltage gain. If you "add" the gain to the input sensitivity, you get rated output voltage of the amp.
What I am trying to find is this,can I run both power amps 29 and 20.6 at the same time through one pre amp and get the same volume level to the speakers.In other words will one set of speakers running on the 20.6 be loader than another set of speaker in another room using the 29 amps
Hope you can help
The volume will be the same only if the voltage gain for the two amps is the same. However, even if the volume is the same, the two systems will sound different. If the systems are in different rooms this probably won't matter, but then neither would different volumes matter, right? I guess I am not sure what you are asking. I highly doubt the two amps will have the same voltage gain, but the only way to tell for sure is to either know the gain outright, in dB, or to know the amp's voltage sensitivity, i.e. how many volts input to the amp will drive it to full volume. An example could be 2 volts to give 200 wpc. From this figure you can figure out the gain knowing the input voltage and the impedance of your speakers.
Sorry for confusion on this question,but I was asking on behalf of a feiend and did not understand what he was looking to do,I know now and this is what he is looking to do.He has two sets of amps the 20.6 and the 29 he wants to use bot sets of amps to bi amp his speakers one set of amps for lower and the other for higher,and he is asking would they blend ok in both volume and sound qaulity
I found the owner's manuals online: the 29's at marklevinson.com and the 20.6's at hifiengine.com. Gotta love the internet.
Comparing the specifications for both amps, the 20.6 has 26.9dB gain for 40V rated output. The 29 has 26dB for 30V output. The input sensitivities aren't given so I calculated them based on this information. Unfortunately, they aren't the same. Scaling both to a 30V output, the 29's is 1.5V and the 20.6's is 1.35V. This may not sound like a big difference, but in my experience with horizontal biamplification (which I currently do in my system), it will definately be audible.
However, there is a chance that the speakers he is using would have a "balancing" resistor between the lower and upper crossovers that "could" go some distance to alleviate the problem since it will be effectively removed when he takes the jumper straps off his biwire posts. The sensitivies aren't too far off so he should try both amplifier combinations and see if either of them works with his speakers, room, and tastes. Who knows? He might get lucky.
It would be preferable to have the higher-powered amp on the bass but the opposite experiement won't cost anything to try. If both fail, the only option (short of changing amps) is to use an external crossover to match the gains but that represents an extra pair interconnects and a potentially costly piece of gear....
Sound quality-wise, I personally feel that (again, in my personal experience) the amplifier "voicing problem" some people refer to in horizontal biamping is swamped out by the different driver configurations that the individual amplifiers see. In other words, damaging the sound quality by horizontal biamping is rare because bass drivers can't sound like midranges and tweeters in any case. It simply boils down to an EQ effect, either beneficial or detrimental depending on the circumstances. This is assuming the bass drivers are truly bass drivers and prove it by having a suitably low crossover point, such as 200Hz.
But a key point to make here is that the extra head room and power his amplifiers would gain would go a long way to making the soundstage bigger, dynamic range larger, and fine gradations kept intact. So if anything, he should get an improvement by horizontally biamping. Of course, this is also assuming he can get perfect gain agreement between both amplifiers.
Dear Alwyn: As important as is the input sensitivity and voltage gain there is ( at least 9 one critical subject that your friend has to take in count: both amplifiers sound diferent, its quality performance is diferent and not closer each other, so your friend could experiment a sound that is far from be : natural well tone balanced. The 20.6s ( that I own ) are in a diferent audio league than the 29 ( that I know very well ).
Now, like Arthur say: he can try it anyway.
regards and enjoy the music.
I would just add a little footnote to all your kind comments in reply to my question,and its this.I live in the uk.and yet if ever I need help and advise in the hi-fi field I come to Audiogon in the us. to get it,this forum has brains and is always friendly,totaly different to what I find over here.
One agai thank you