OK. So are not some loudspeakers designed with very low impedences so that they will audition better because they are louder? (and I understand that this is not the same as sensitivity.) Does that not relate to input impedence in amplifiers?
Not really. The fact of the matter is that all amplifiers have less distortion driving higher impedance speakers. Some speakers are lower impedance as some solid state amps will make more power (sound quality is being traded off for sound pressure in this case). Many speaker designers don't realize that though. And this **is** in fact what we are talking about with the term 'sensitivity'. But none of that has anything to do with the input impedance of an amplifier.
www.audioholics
The above site agrees with some above comments from Bombaywalla and others. To summarize, according to the source, high input impedence in SS causes high voltage gain which in turn causes noise. It can also cause bandwidth to decrease. And finally it can introduce DC offset.
This is mostly bogus! Input impedance has 100% nothing to do with gain. A high input impedance does not have to have anything to do with noise either unless the design and execution is shoddy. We get 300KHz with 100Kohm input impedance, clearly the bandwidth thing is problematic. Think about a 6AU6 vacuum tube which is very high impedance but can operate easily at 10MHz. Finally, input impedance has nothing to do at all with DC offsets, and cannot introduce it.
I would stay off that website as it is a source of misinformation, and that is being kind.
