It's like in business buy low, sell high.
Amp-Pre
Low output impedance drives high input impedance. The higher the difference the less sonic losses in the signal path.
If for some reason you can't neglect an output impedance than it's in the circuit with the input impedance of the next component where you sustain voltage drop. For example you're about to get an amplifier with input impedance of 10k and you've heard the super great reviews on preamp that apperently without your knowlege have 1.5kOhm output impedance. When you connect these two units that had superior reviews on the magazines and other media, they don't sound right not only to your ear, but to the ear of anyone visiting you to listen to your rig and you'd ask yourself why???
Simply because your loss is near 15% on the path from amp to preamp. This causes diminished details espesially on the slopes of the frequency bandwidth of both components or they appear in the dissonant way when you turn the volume up.
The rule of 1:10 of output/input impedance is acceptible and within common sence, but leaves with very limited volume range when the sound is natural and pleasant. To me isn't enough. Maybe it's enough for monotonic and compressed signals, but for wide dynamic range certainly should be higher.
Power Amplifier (and/or integrated)
I personally prefer to overpower speakers and consider only models with larger than 100Wpc. Low sound frequencies can be considered as DC when designing a linear circuits. Voice coils are inductive by nature and inductor has Zero impedance at DC! Low audiable frequencies >50Hz require 2...3x higher power to induce EMF and mechanical vibration than the rest of frequency bandwidth. There's no way that 20Wpc amp will be able to bring any voice coil to audiably move at bellow 60Hz of even high-efficiency speakers... maybe marketwise, but not engineeringwise. Another words no power -- no bass.
Integrated amplifier is the one having near perfectly matched both stages in one unit. It saves you space, wires and nowdays easy to find the one with the power you need. Another words highly marketable and recommended vs. separates. So forget about the first para if you're realy planning to go integraded -- the best to begin with and after playing with separates(swapping reconnecting like an 8yo) grow up and get one again!
Speakers.
As I've mentioned above, speakers either high or low efficiency, have its own impedance curves that you should pay more attention. For direct-coupled SS amplifiers(no capacitor or transformer on the output stage) the speaker selection is substantially wider due to their low output impedance. For transformer-coupled SS or tube amps the degree of impedance curve stability is a factor to consider. For directly-coupled tube amplifiers OTL you should only consider the lowest impedance value to be within the amplifier specified range of loads. They react positively on the impedance increase.
Amp-Pre
Low output impedance drives high input impedance. The higher the difference the less sonic losses in the signal path.
If for some reason you can't neglect an output impedance than it's in the circuit with the input impedance of the next component where you sustain voltage drop. For example you're about to get an amplifier with input impedance of 10k and you've heard the super great reviews on preamp that apperently without your knowlege have 1.5kOhm output impedance. When you connect these two units that had superior reviews on the magazines and other media, they don't sound right not only to your ear, but to the ear of anyone visiting you to listen to your rig and you'd ask yourself why???
Simply because your loss is near 15% on the path from amp to preamp. This causes diminished details espesially on the slopes of the frequency bandwidth of both components or they appear in the dissonant way when you turn the volume up.
The rule of 1:10 of output/input impedance is acceptible and within common sence, but leaves with very limited volume range when the sound is natural and pleasant. To me isn't enough. Maybe it's enough for monotonic and compressed signals, but for wide dynamic range certainly should be higher.
Power Amplifier (and/or integrated)
I personally prefer to overpower speakers and consider only models with larger than 100Wpc. Low sound frequencies can be considered as DC when designing a linear circuits. Voice coils are inductive by nature and inductor has Zero impedance at DC! Low audiable frequencies >50Hz require 2...3x higher power to induce EMF and mechanical vibration than the rest of frequency bandwidth. There's no way that 20Wpc amp will be able to bring any voice coil to audiably move at bellow 60Hz of even high-efficiency speakers... maybe marketwise, but not engineeringwise. Another words no power -- no bass.
Integrated amplifier is the one having near perfectly matched both stages in one unit. It saves you space, wires and nowdays easy to find the one with the power you need. Another words highly marketable and recommended vs. separates. So forget about the first para if you're realy planning to go integraded -- the best to begin with and after playing with separates(swapping reconnecting like an 8yo) grow up and get one again!
Speakers.
As I've mentioned above, speakers either high or low efficiency, have its own impedance curves that you should pay more attention. For direct-coupled SS amplifiers(no capacitor or transformer on the output stage) the speaker selection is substantially wider due to their low output impedance. For transformer-coupled SS or tube amps the degree of impedance curve stability is a factor to consider. For directly-coupled tube amplifiers OTL you should only consider the lowest impedance value to be within the amplifier specified range of loads. They react positively on the impedance increase.