About Units of Analog Audio Measurement
Professional audio equipment typically uses higher voltage levels than consumer
equipment, and it also measures audio on a different scale. Keep the following points
in mind when using consumer and professional audio equipment together:
 Professional analog devices measure audio using dBu (or dBm in older equipment).
0 dB on the audio meter is usually set to +4 dBu, which means optimal levels are
4 dB greater than 0 dBu (.775 V), or 1.23 V.
 Consumer audio equipment measures audio using dBV. The optimal recording level
on a consumer device is –10 dBV, which means the levels are 10 dB less than 0 dBV
(1 V), or 0.316 V.
Therefore, the difference between an optimal professional level (+4 dBu) and consumer
level (–10 dBV) is not 14 dB, because they are using different signals. This is not
necessarily a problem, but you need to be aware of these level differences when
connecting consumer and professional audio equipment together.