The Heritage Audio OST 10 v2 is a sophisticated module frame for API's 500 series. Unlike other 500 series racks, the OST 10, like its predecessor, supplies each module with power in isolation from the others. In this way, the user is spared interference and noise associated with the power consumption of individual modules and transmitted to others via the power supply. The inherent noise of microphone preamplifiers in particular 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. In this version, an LED chain also allows the power supply for each individual plug-in unit to be monitored.

An important new feature introduced by Heritage Audio is a link function: Using switches on the rear panel, each slot can be connected directly to its neighbor without the need for patch cables.