The Mackie HM-400 is a 4-channel headphone amplifier in a 19" rack format, offering incredible versatility and excellent sound quality in a single compact unit. It is perfect for professional studio applications, rehearsal sessions, and more. The HM-400 also features a main input with volume control, stereo outputs, auxiliary inputs, a channel equalizer, and a total of 12 headphone outputs. **About Mackie** Mackie is one of the leading brands in professional audio, from speakers to mixing consoles, catering to both studio and recording equipment. Founded in Seattle in 1988 by Greg Mackie, a former Boeing employee who started by designing small compact mixers and guitar amplifiers in his spare time. In recent years, the brand has become a favorite among those seeking high-quality audio solutions at very reasonable prices. Its catalog includes all kinds of mixing consoles, studio monitors, microphones, headphones, and everything you need for your Home Studio or live recording setup.