In this paper, we propose a set of audio features to describe the quality of an audio signal. Audio quality is here considered as being modified by the chain of processes/effects applied to the individual instrument tracks to obtain the final mix of a musical piece. Thus, the quality also depends on the mastering processes applied to the final mix or the signal degradation caused by MP3 compression. To evaluate our proposal, we created a large set of artificial mixes and also used real-world studio mixes. Using unsupervised and supervised classification methods, we show that our proposed audio features can detect the processing chain. Since this processing chain applied in professional studio has evolved over the years, we use our audio features to directly predict the decade during which a music track was recorded. Index Terms— audio quality, music information retrieval , audio reverse-engineering, database indexing, music remixing.