Millennia HV-3D~4 4 Channel Class A Microphone PreampThe HV D4 is a rackmountable four channel version of the HV 3 mic preamp. High resolution (HR) gain switches are standard. BK and DC options available. Features: Unsurpassed ambience retrieval Transformerless design with matched hi speed discrete transistor octet has 23 dB input headroom: no attenuator "pads" needed Uncolored timbral accuracy at all dynamic levels Entirely balanced audio path with precision components maintains signal integrity: THD