Preamp gain ???

For many people the issue is too much gain, resulting in operating the pre w near max attenuation and at the lower end of the volume control's range. Under these conditions you may be in that portion of the attenuator where channel matching is not v. good and, particularly in the case of a stepped attenuator, where the "steps" are too coarse to give you good level control. Step x, too soft, step x+1 too loud. typically, the perceived volume difference between steps is less as you go to less and less attenuation (higher spls). Not knowing much at all about the technical side of electronics/circuits, I am guessing that this is due to the logarithmic relationship between power output and spls- Need 10x the power (wattage) to sound 2x as loud. So it really does NOT matter much as long as you are able to operate in the middle of the controls range. Believe me, I had a CAT SL-1 w stepped attenuator and 2 clicks up from 0 was too soft and 3 clicks up was "kick out the jams"! A real PITA.

Slikric,
It depends on the output of your source i.e. how many volts and also the sensitivity of your amplifier and speakers.The higher the source out put, the less gain needed from your preamp. The more senitive the amp(for example an amp with a sensitivity of .5volts would require less preamp gain than an amp with a sensitivity of say 1.5 volt to reach a given volume level). The same with speakers, 95db sensitivity would need less gain than a 88db speaker to reach a given sound volume. Most digital sources will be 2 volts or higher and often high gain preamps are`nt needed, 10 db of gain should be plenty. With too much gain in a system your useful range on the volume control will be quite limited i.e. 7-9 oclock, as above that level the sound becomes to loud, and fine tuning is very difficult.

And Charles1dad summarizes all of the issues perfectly on either side of the pre-amp. They all contribute to the "problem" of excess gain which manifests itself in having to operate the attenuator in a non-optimal part of its range. The pre-amp is also the place where you can (usually) have the manufacturer easily resolve the "problem". You can easily experiment w low cost line attenuators at the amp's input to determine how much the pre-amp gain needs to be reduced or use one the better 10 dB attenuators like the Rothwell for a slightly more expensive, easily reversible fix. If you do that and use heavy cables, make sure you provide some support under the attenuator or else, IME, you are likely to have a failure of one of the jacks.

i would say this: i think it unnecessarily complicates the problem is you are trying to solve amplifer-speaker interface problems at the preamplifer. it is more manageable to decompose the problem; with regard to the preamplifier the focus should be on the input signal levels from the sources. you can then focus on the output signal from the preamplifier but most reasonable preamplifiers should be able to drive a power amplifer into clipping at maximum output voltage (such that in reality you would likely never get anywehere near the maximum output voltage). then you deal with issues of speaker sensitivity sepearately but that is more concerned with whether the power amplifier is up to snuff to drive the speaker load.

so the issue at the preamplifier is the input sensitivity of the preamplifier and the input signal levels from the soruces. i would expect that the input sensitivity of a preamplifier is going to be around 500mv, which is the line voltage signal level that you tend to get from many sources. cd players tend to be a bit higher. where you really need to watch out is when using phono sources. here you have to make sure that the phono stage provides sufficient gain for the given cartridge. ideally you want the output signal level from the phono stage to come in at around the input sensitivity of the preamplifier.

so once you have managed the input signal levels from the sources then you want to make sure that the preamplifier can drive the output voltage to the power amplifier. as i stated, the voltage amplitude should be sufficient but you probably want to check the preamplifier manual to find out what is the minimum input impedance that the preamplifier expects to see at the power amplifier, then check the input impedance of the power amplifier to make sure that the specified input impedance is considerably higher than the minimum needed by the preamplifier.

that's the analysis that you should do at the preamplifier. what you want to determine is whether the sources are providing adequate signal levels to the preamplifier and that the preamplifier is providing an adequate signal level to the amplifier. a side benefit of this analysis is that the signal being provided to the power amplifier will likely have a better signal to noise ratio, which, if the amplifier is up to snuff, will result in a better sounding system. issues related to the interface between the power amplifier and the speakers should be addressed in an analysis of the capabilities of the power amplifier.