The Heritage Audio OST 6 v2 is a sophisticated module rack for API's 500 series. Unlike other 500-series racks, the OST 6 supplies power to each module in isolation from the others, just like its predecessor. In this way, the user is spared interference and noise related to the current consumption of individual Module modules, which is transmitted to others via the power supply. Especially, the self-noise of microphone preamplifiers is significantly reduced. At the same time, each module receives a supply current of up to 400mA, so that even high-consumption devices such as Class A preamps (e.g. from Neve) or tube circuits can be optimally supplied.

As an important innovation Heritage Audio introduces a link function: Via switches on the back, each slot can be directly connected to its neighbor without the need for patch cables.