The 1U rack or desk mount iDR-4 is the main unit in the iDR system having all the DSP (digital signal processing) power needed for 16 input and 16 output channels. The iDR-4 has a total of 6 balanced audio inputs including 2 XLR analogue mic/line and 4 TRS jack line inputs. It has 6 balanced audio outputs including 4 XLR analogue land 2 TRS jack line outputs. You can add a further 8 inputs and/or 8 outputs bringing it up to a maximum 14x14 matrix by plugging in the iDR-in and/or iDR-out audio expanders. The signal can be routed at three key points: the input source patch bay, central crosspoint matrix, and output source patch bay.

Although the iDR does not work with networked audio, the expanders can be located up to 250 metres away so providing remote analogue audio inputs and outputs connected using CAT5 cables. You can also daisy chain multiple iDR-4 and iDR-8 units in a distributed system. The units are linked using an 8 channel wide bus which plugs into the digital expander ports. Maximum matrix at any unit is 16x16 which includes the interconnecting bus. Several iDR units can be linked in this way, but you can have only one iDR-in and one iDR-out expander per system. This is described later.