Troubadour platform is an open-source personalized and adaptive web platform for ear training. The platform was developed to support music theory classes with automated music-theory-related exercises. In this paper, we present our three-stage development methodology, which incorporated the needs and feedback from both teachers and students to build an engaging music-theory e-learning platform with gamification elements. We developed and evaluated the platform with students of the Conservatory of Music and Ballet Ljubljana. The students of the 1st and 2nd year of the programme were split into two groups-the control group used the traditional way of learning, while the test group augmented their learning with the Troubadour platform. The evaluation results show an increase in exam performance and corroborate the platform's user experience as one of the key reasons for the students' engagement.