The Bass Traveler from M-Audio is a two-channel, rechargeable headphone amplifier capable of powering two sets of headphones, while ensuring crisp clear sound. The unit also features an integrated “Boost” switch offering flat, medium, and high settings to optimize the sound for any headphone. The rechargeable Lithium-polymer battery offers up to 8-hours of use from a single charge. The TRRS connections are compatible with most popular in-line remote control headphones. The Bass Traveler also ships with a TRRS connection cable and a micro-USB charging cable.

The Mackie HM-4 is a 4-way headphone amplifier designed to provide simple and effective headphone amplification for artists, musicians, and engineers monitoring through headphones in home, project, commercial, and mobile-recording studios. Its single 1/4″ TRS stereo input and four 1/4″ TRS stereo outputs allow you to distribute a stereo source to up to four pairs of headphones.

Each output is controlled via a dedicated level knob, allowing varied listening volumes for each person. The compact heavy-gauge steel chassis offers rugged durability and a convenient power status indicator on its front panel. Use the included 12 VDC power supply to power the HM-4.

The Mackie HM-400 is a rack-mountable, 4-channel headphone amplifier designed to provide versatile headphone amplification for artists, musicians, and engineers monitoring through headphones in live stage applications and home, project, commercial, and mobile-recording studios. It features a stereo main output via XLR and 1/4″ jacks and twelve 1/4″ TRS stereo headphone outputs—three per channel—fed by a customizable blend of inputs.

The Mackie HM-800 is a rack-mountable, 8-channel headphone amplifier designed to provide versatile headphone amplification for artists, musicians, and engineers monitoring through headphones in live stage applications and home, project, commercial, and mobile-recording studios. It features two stereo main outputs via four 1/4″ jacks and sixteen 1/4″ TRS stereo headphone outputs—two per channel—fed by a customizable blend of inputs.

Two stereo main inputs via four 1/4″ jacks can be combined with a per-channel 1/4″ stereo aux input. Each channel offers stereo/mono mode switching, input selection, and output level adjustments. 7-segment LED meters display main input and per-channel output levels.

The Micro DAC from M-Audio is a USB digital-to-analog (DAC) converter with two outputs�one analog and one digital. Taking the form of a slim USB stick, the Micro DAC plugs right into your computer or laptop, and, once there, transforms your digital signal into audio of a higher quality than a typical headphone jack. With the Micro DAC, you plug your headphones into the port on the side; for high-impedance headphones, you can flip a gain switch to boost the analog signal, thereby driving the volume to higher levels. An optical output can transfer pure digital signal from the Micro DAC to other digital sources.