Professor:  What do dB ratings mean?  Is 20 db twice 10dB?  NO! dB do not work like regular numbers.  dB is just the logarithm of the ratio of two numbers.  The two numbers have to have the same units, such as watts (power) or volts.  We like to use dB just like logarithms because it is easier to add than to multiply in our heads.  If the gain is 26 dB it means the output is 26 dB greater than the input.

    +3dB is 2X power
    +6dB is 4X Power (2 x 2)
    +9dB is 8X power (9/3 = 3  so 2 x 2 x 2)
    10dB is 10X power
    20dB is 100X power (10 x 10)
    26dB is 400X power (10x10x4)

    -3dB is 1/2 power
    -6dB is 1/4 power (1/2 x 1/2)
    -9dB is 1/8 power ((1/2 x 1/2 x 1/2)

-3dB is 1/2 power.  Power is proportional to voltage squared.  This is because if you cut the voltage in half, the current is also cut in half, and since power is voltage times current, and both current and voltage are cut in half, power is cut to 1/4.

Professor: What does hum 120dB below the peak output mean? Noise is measured in decibels (dB). The noise floor of a normal CD is 96dB below peak output, a limitation of 16 bit encoding. If you go from 96 dB to the 120 dB of the SLC-A300, there is a difference of 24 dB. This is not 25% better, because dB are not like normal numbers. With dB, every 3 dB lower is half the noise. So the SLC-A300 is over 100 times quieter. (With hum, the more dBs below the peak output, the quieter it is.) This means that the hum components are not louder than the noise floor at only 1 watt output. In other words, you can enjoy the full dynamic range of a CD at 1 watt output without the hum degrading the CD’s noise floor.

Golden Ears:   Perform the thumb print test yourself. (This is a fanatic’s test for an entire system.) Clean a CD. Then put a thumb print on the bottom side of the CD. Play the CD and listen carefully - the CD player will compensate for the thumb print, but it will not make a perfect correction. Then clean the CD and listen again. If you can hear the difference with and without the thumb print, then your system is capable of revealing great spatial detail. If your system does not pass this test, then the fault is not in the SCL-A300.