A, this bottom noise amplifier shall be measured how? Used monster beats importers digital multimeter friends all know, if the table dial millivolt to block, pens and hung up when anything not answering the multiplier and jumping about figures have been started. Numbers spool little criterion 3, 5 millivolt, many tens mv. Is this the precision of the multimeter so low that the magnitude of millivolt not measuring parameters? Not as well. As long as the two pens and docking with the multiplier and stable soon back to zero. So just Numbers spool come in? Because there are scattered around space of stray electromagnetic interference signals, and the multimeter resistance is bigger, can very sensitive to jamming signal to accept to reason. Once the pens and docking, the interference of electromagnetic signal is through the pens and short sub off, then a multimeter is shown in stable back to zero digital, to show that it can measure of minimum signal range is. On the other hand amplifier, if you empty the volume and pick up input terminals the largest open, then hear noise, and just as the truth of the multimeter, has quite a lot of electromagnetic interferences noise. That you find a unplugged the signal of the plug, and put the plug in the two ends into short circuit, then hear what??? May what also can’t hear or very small noise. This is the bottom of the amplifier noise. So, you might ask, turn the volume down to the smallest not can also shut? Is that sometimes may be so of, for example, the volume in the front of the circuit potentiometer. But, also some circuit is not in the front volume potentiometer, its front perhaps other circuit components or wiring, you put it off to a minimum, reflect the noise is just after the noise of the circuit potentiometer. So, the correct measuring method should be input short sub, the volume of maximum noise is the bottom of the amplifier noise.