The dampening factor is called a dampening factor because is dampens the movement of the loudspeaker cone. If you send a brief pulse of current into a loudspeaker voice coil, the voice coil will move. It will also keep on moving for a while after the pulse is over. Just like giving a push to a child on a swing. Ideally, we want the voice coil to stop immediately after the pulse is over. The friction in the cone suspension performs this, but we can make it quicker by adding electrical "friction". The voice coil generates a voltage due to the movement, so by connecting a 0.01 Ohm resistor across the loudspeaker terminal, we draw energy out (mainly as heat energy in the voice coil), and thereby dampen the movement of the voice coil. The voice coil of a 8 Ohm loudspeaker unit typically has a 6 Ohm DC resistance. If you connect 0.01 Ohm to the terminal on the loudspeaker unit, the current is limited both by the 6 Ohm internal resistance and the 0.01 Ohm external resistor. The total is 6.01 Ohm. Dampening factor is 800. Let us assume the voice coil generates 1V, then the current is 1/6.01A=0.166A If we use a 1 Ohm external resistor, the total resistance is 7 Ohm. Dampening factor is 8. The current will be less 1/7A=0.143A, and therefore the energy is drawn slower. If the external resistance is 0.1 Ohm, dampening factor is 80, the current will be 1/6.1A=0.164A. This is very close to the result with 0.01 Ohm. In fact, only 4% less energy, as energy is current x current x resistance. Doing some more calculations and plotting a graph, you will find that up to a dampening factor of 25, you get significant improvements, and that a value of more than 25 in dampening factor is of little use. Above 100, a higher dampening factor hardly makes a difference. However, to get a dampening factor of 25 for a 4 Ohm loudspeaker unit, you need 0.16 Ohm of total external resistance. You rarely connect the amplifier directly to a loudspeaker unit. In real life, you must therefore include the resistance in the loudspeaker wires and the crossover coils, the resistance in both parts of the loudspeaker cable, and add them to the output impedance of the amplifier. So to be safe, an amplifier output impedance should be about 0.04 Ohm. This is the same as a dampening factor of 200 in 8 Ohm. Some famous dynamic High-End loudspeakers go down to 2 Ohm, requiring a dampening factor of 400 ref 8 Ohm to be safe. Of course, if the crossover includes a series resistor to adjust the level, a high amplifier dampening factor is wasted for that loudspeaker unit. Now, the dampening factor in an amplifier is normally dependent on frequency. Usually, the output impedance rises at higher frequencies due to the protection coil. This coil is intended to protect the amplifier against capacitive loads. In the GamuT D200, a Direct output is taken before the protection coil. At 5kHz, the output impedance is 0.03 Ohm at the Direct output, and 0.12 Ohm at the normal coil output. At 100Hz, the output impedances are both low, specifically 0.02 Ohm for the Direct output and 0.03 Ohm for the normal output. If your loudspeaker is a dynamic type with high quality capacitors, no resistors in the crossover, and you are using low impedance cables, then you will gain a better dampening factor at 2-20 kHz with the direct output. This can be heard as significant better transient response in the midrange unit or in midrange/tweeter.