The aim of this study was to correlate musical aptitude scores derived from two tests based on the same structural model for musical aptitude in a sample of 9- to 13-year-old children. We controlled for the influences of socioeconomic status (SES; measured by parents’ education), the amount of music lessons, and general cognitive abilities (i.e., IQ). The sample comprised 89 (46 girls) 9- to 13-year-old children. We applied two different tests by Edwin Gordon: Intermediate Measures of Music Audiation (IMMA) and Advanced Measures of Music Audiation (AMMA) to measure musical aptitude. As control variables, IQ, socioeconomic status, and amount of music training were assessed. A hierarchical multiple regression analysis revealed that the total score of the IMMA together with the control variables could not predict the total score of the AMMA. Furthermore, regression models for each of the subtests were also not significant. With respect to the control variables, we revealed an association between the IMMA and socioeconomic status as well as amount of music training. We conclude that even tests that are based on the same structural model of musical aptitude were not associated significantly. This might indicate problems of validity. Additionally, it seems to be difficult to assess musical aptitude independently of influences from music training and SES. Ultimately, this may support the notion that we still need valid musical aptitude tests for this particular age group.