The devices of the arfi series work with DC 6-9V. The arfi-psu in housing format is an alternative to the standard mains adapter included with afis and afi. The AD converter arfi-adc2 and the DA converter arfi-dac2 are always shipped together with the afip. The arfi-psu has four 6V outputs to 4-pin XLR to power the devices of the arfi series. This is a hybrid concept, a switching power supply for AC/DC conversion followed by linear regulators, separated for each of the four outputs, thus fulfilling the requirements of the current Eco-Design guidelines. Despite this, the quality of the output voltage outperforms most traditional linear power supplies. The careful filtering of the mains connection means, in addition to good starting conditions for the AC/DC conversion, as few adverse effects on the electrical grid as possible.