Analog Devices, at

http://64.233.167.104/search?q=cache:_2Fi1tqs_cUJ:www.analog.com/Analog_Root/static/techSupport/designTools/interactiveTools/dbconvert/dbconvert.html+dBu+dBv&hl=en&ie=UTF-8

has a converter calculator for various dB standards, as well as definitions of them.

For best signal to noise ratio, you would want as large an input signal (say, from your CD or DVD player) as possible and use the least amount of gain of the preamp (or 950) in order to drive the power amps to desired output.

What soundhound is doing in regards to using his active crossover, with nice sounding, but noisy video buffers is maximizing the signal to noise ratio of the active crossover by giving it a really big input signal. When he attenuates the large output of the active crossover, he is also attenuating the noise inherent in the output of the active crossover. Similarly, in your case, you give the preamp (or 950) a big signal and use the preamp (or 950) to attenuate the signal (and the noise in it) to a reasonable level for your power amp.

If you set things up to use your preamp (or 950) at maximum gain, then any noise coming into the preamp, or generated at the preamp's input stages, will be made much worse. Beings you are using your preamp at maximum gain, the input signal from the source (CD or DVD player) will have to be small so as to not overload the preamp or power amp.

Paul

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the 1derful1

Thanks for the link, Paul. This program is really convenient. It does all the conversion in one single package. Nice.

Now I understand soundhound. I usually use the gain control on the amp to attenuate the signal to my desired volume. Because I think running unnecessarily low signal levels through cables and equipment is bad for optimizing signal-to-noise ratio; it's much better to have strong signal levels that are well above the noise floor, but not clipping at early signal stage. Then the final stage, the power amplifier, doesn't need as much gain. Consequently, the residual hum and noise doesn't get amplified as much, either. I think setting up the gain structure this way results in much less audible hiss and hum in the system.

You are right - the higher the signal level is while it traverses through each component and along interconnects, the higher it will be above any potential noise picked up along the way. This is a simple (and free) tweak that I'm surprised more people haven't picked up on as a very effective way to reduce noise.

Of course one thing to watch out for is that the component stage that does the initial signal boosting must be quiet in itself so that it doesn't contribute it's own noise.