This paper illustrates the main principles for loudspeaker compensation and compensation of the room acoustics that are used by Dirac Research and that have resulted in the technologies Dirac Live(R) for single-channel compensation and Dirac Unison for joint multi-channel compensation.A first main aim is to control not only the frequency domain properties of the system but also the time domain properties: The impulse responses as measured at different listening positions.In particular, we strive to reduce the "pre-ringings" (pre-echoes) that would otherwise result in an un-natural sound experience.Secondly, we use dynamic models of the sound system that are based on measurements at multiple listening positions.This is important for obtaining a robust design that works over an extended region to provide a large spatial area with good sound quality.Third, we may jointly optimize multiple loudspeakers to better control the sound pressures at different listening positions.This is done by precise phase control of the individual loudspeaker transfer functions at low frequencies.Joint optimization of a set of loudspeakers results in more distinct bass performance, better robustness of the compensation and better control of the impulse responses at different listening positions.