IEC 61606-1:2009(E) is applicable to the basic methods of measurement of the audio characteristics of the digital audio part of audio and audiovisual equipment for all of consumer use, professional use and personal computer. The common measuring conditions and methods, described in this standard, are used for the measurement of the performance characteristics of equipment having an audio bandwidth equal to approximately one-half of the sampling frequency of a system, where the audio information is processed in the form of digital data. CD players, DAT recorders, digital amplifiers, digital sound broadcast receivers and television broadcast receivers with digital sound are examples. It describes test methods for equipment which has digital input with analogue output and analogue input with digital output. Future revisions of this standard will cover digital-in/digital-out and analogue-in/analogue-out tests. It constitutes a technical revision. The significant technical changes with respect to the first edition are the following: - changed the period of preconditioning; - add A weighting filter in measuring instruments; - correct the wrong reference number; - some inappropriate descriptions have been improved.