Free shipping on most orders over $199!* - Showroom Closed / Pick-up Available

Metric Halo ULN-8 mkIV Audio Interface

Model: 000-5004

Metric Halo ULN-8 mkIV Audio Interface
Metric Halo ULN-8 mkIV Audio Interface
  • Free Shipping!
  • Not In-Stock - Available to Order 
  • Not yet reviewed

About: Metric Halo ULN-8 mkIV Audio Interface

For over 20 years, Metric Halo sound has been beloved by musicians and audio engineers the world over.

Our 4th generation mkIV analog and converter stages enhance the already world-class design of the ULN-8 to provide you with warm yet detailed, open & musical sound that captures and presents your work in its best light.

ULN-8 mkIV Key Hardware Features

Whether you are on location, in the studio or the mastering room, the ULN-8 mkIV has what it takes for you to get the job done.

ULN-8 mkIV is built on Metric Halo’s core 3d Technology, so it interoperates seamlessly with all existing MH 3d interfaces.

Since it is amazingly flexible, expandable and future-proof by design, your system always scales to meet your needs. Each unit includes these hardware features:

  • Metric Halo’s unique 3d Core Digital Engine with MHLink
  • 8 channels A/D with Analog Trim
  • 8 channels D/A with Analog Gain
  • Stereo Headphone
    • Dedicated HP D/A and Analog Gain
  • Ultra-low converter latency
  • Converter latency reduced by 85% compared with previous generation
  • Round-trip through Converters + Mixer + DSP + Monitor:
    •   ≈ 0.9ms @ 44.1k
    •   ≈ 0.2ms @ 192k
  • 8 channels MH ULN-R preamps
  • 2 channels Guitar/Bass DI inputs
  • 8 channels AES Output
  • 8 channels AES Input
  • MIDI I/O
  • 128 Channel x 64 bus mixer
  • Integrated DSP
  • Full support for 192k
  • Detailed Front panel metering
  • FP control with dedicated gain knobs
  • IR Remote Control support
  • MH EdgeBus Card slot
  • MHLink Gigabit Ethernet connectivity
  • USB-C connectivity
  • Low power, cool-running design with no fans

The mkIV excels in these key areas:

  • Tracking
  • Mixing
  • Mastering
  • Live
  • Monitors
  • Production
  • Remote Mic Pre
  • A/D/A
  • Active Analog Split
  • Digital Snake
  • DSP Processing
  • Format Conversion
  • Headphone Amp
  • DI
  • Meter Bridge
  • Monitor Control
  • Cue Playback
  • Session
  • IR Remote
  • Tactile Control
  • Wireless Control

Integration for the Win

By implementing all the functions of a complete end-to-end signal chain solution in a single package, the ULN-8 mkIV is able to provide unprecedented capability and quality in a lightweight, low-power, single rack space unit. This integration has significant benefits in the form of reduced setup time and greater reliability, reduced cabling, weight, power consumption and cost, even as it provides unprecedented flexibility and performance.

The MHLink routing and transport architecture allows you to build a system with units distributed up to 100 meters apart with no added latency.

MHLink's auto-configuration and hardware aggregation make it so the entire system appears to the host computer as a single unified interface. Audio, command and clock transport with up to 256 channels of audio (at 192k) is accomplished with light-weight, inexpensive, readily available Cat 5e cabling.

The new mkIV design is eco-friendly and uses very little energy to provide its incredible performance and power. Even when every mic channel is powering a 48v phantom mic, the ULN-8 mkIV only consumes 25 watts, and without phantom uses less than 21 watts.

This low-power design allows the mkIV to run cool and stable. No noisy fans required.

Metric Halo Sound

The sound of an audio product is more than the the sum of its parts. You can’t simply look at the components used and determine how something is going to sound. Excellent audio requires careful attention to detail and the tuning of every element of the entire system; this includes the analog stages, the power system, the clock and the converter itself. As all of these interact with each other in nonlinear ways, it is the system that determines the performance, and not any of the individual parts.

The A/D/A converters in the ULN-8 mkIV are DC-coupled to the analog I/O stages so they introduce extremely low phase distortion. The D/A has no low-frequency filtering. The A/D converters have an extremely low frequency DC blocking filter that calibrates the input path and removes DC offset with minimal phase shift.

Every element of the design combines to give you a warm, open 3-dimensional sound that is highly revealing and yet totally natural. Metric Halo mkIV sets a new standard.

It’s digital with soul.


The ULN-8 mkIV includes 8 channels of Metric Halo’s renowned ULN-R preamps. These boutique preamps are famous for their pristine, low-distortion, completely unveiled sound.

The ULN-R preamp provides up to 90 dB of digitally-controlled analog gain in precisely recallable 0.5 dB steps. Each input supports independently switchable P48 phantom power.

The combination of the super transparent ULN-R preamp and Metric Halo’s exclusive insertable Character Component Modeling Processing provides flexibility and sound quality that’s unavailable on any other device. You can transition from a wire-with-gain pre to a gooey tube pre or anything in between; every input can have the right Character for the sound you want.

The preamp input path on the ULN-8 mkIV always has preamp gain control and has DC blocking for the phantom power, it also supports input levels of up to +20dBu with no fidelity reducing pads, so you can handle high SPL with sensitive mics as well as you can handle extremely low SPL with insensitive mics (like ribbon mics and low output dynamics) while maintaining ultra-low noise.

The high maximum input level of +20dBu also means that you can use the mic pre input path as an alternative line input path. This feature can be used with the monitor controller to access an additional 8 selectable analog inputs as external sources.

The ULN-8 mkIV input path features an integrated analog send (pre A/D converter) which allows the unit to be used as remote controlled analog preamp. MHLink connectivity and control means that your preamps can be really remote (up to 100m away from your control interface) when you need them to be.

The preamps also offer a send/return mode where the amplified signal from the preamp is sent to the analog send and the line input is used for the return to the A/D converter - this allows you to patch analog processing between the preamp and the converter. Finally, you can use the analog send to provide the pre-amplified signal to a backup recording or mixing system; this is a fully analog split that represents a true backup signal with no digital dependencies.


Monitoring is critical to the production process at every stage; you need to be able hear exactly what you are working on. Your monitor chain will be limited by the weakest link in the chain. The ULN-8 mkIV integrates a transparent digitally controlled analog monitor controller to ensure that you can connect directly to your reproduction chain without having to reduce the fidelity of your signal with an inferior monitor control system.

mkIV hardware includes a relay driven shunt mute circuit on all the analog outputs that prevents transients from getting into your power amps and speakers. The mute is designed to be completely out of the circuit under normal monitoring operations. It automatically protects your monitors during power cycles and sample rate changes.

The Monitor Controller in the ULN-8 mkIV provides sophisticated monitor control features that are only available in dedicated monitor controllers that surprisingly cost more than the ULN-8 mkIV.

These features include:

  • Multiple source selection
  • Multiple speaker output selection
  • Output paths can share speakers
  • Per speaker gain and delay
  • Per speaker solo/mute control
  • Output path calibration support
  • Multichannel support from Stereo up to 7.1.4 Surround (Dolby Atmos®)
  • Mono fold-down
  • Mute and Dim
  • Analog gain control
  • Talkback
  • Listenback
  • Multiple cue output support
  • PFL/AFL integration with the mixer

In addition to all these high-end features, the MH Monitor Controller provides unique support for per-output-path configurable signal processing including EQ, Bass Management and protective limiting. Each output path can have its own signal processing, even if the paths share speakers. This allows you to configure alternate monitoring setups with one monitoring system (for example, you could configure the signal processing to provide a band-limited monitoring path or a path that lacks subwoofer reinforcement).

Each ULN-8 mkIV includes a high quality headphone amplifier with dedicated D/A conversion (which is the same quality as the primary D/As in the system), and digitally controlled analog gain control. So you don’t need to add a headphone amp to your system. By default the headphones are configured as a parallel Cue output multed from the Monitor Controller, but you can drive the headphones with an independent mix or you can make them an alternate output for the monitor controller.

Cue Control

In addition to monitoring the mix in your control room, multitrack production requires providing multiple output cues to performers, producers and/or broadcast feeds.

The Monitor Control in 3d is enhanced by a sophisticated Output Cue section that provides you with an arbitrary number of output controls. Each cue can be driven from any of the busses in the system, or it can be set to derive its input from the currently selected source in the Monitor Controller (MC).

Since each Cue can be driven by a separate mix bus from the mixer, they are perfect for routing and controlling independent headphone mixes for individual performers.

Cues can be configured to listen to PFL/AFL (or not). So for producers and engineers, the cue can follow PFL/AFL Solo in the mixer while performer and broadcast cues are unaffected by soloing.

Each cue has an independent output path which can be set to any of the MC supported output types. Each cue controller uses the MC engine for its control of routing, gain, delay and output graph processing, so it can do all the things the MC can do.

Cues form the basis of the routing points for Talkback and Listenback.

Talkback provides the ability to route a specific input to any sub-set of the cues in the system; it also allows you to control the amount that the Cue source signal is dimmed when talkback is active. The Talkback signal is mixed with the selected source.

Listenback provides the ability to route the source that the engineer is currently monitoring through the Monitor Controller to any subset of the cues in the system. This allows playing back a mix of the take to any or all of the monitoring cues in the system without having to re-patch.

Ultimate Console and Mixer Solution

For 3d and mkIV, we designed a new, retina-enabled, 64-bit, cross-platform console application: MIO Console 3d.

MIO Console features a high-impact, modern, flat design with scalable UI elements. With user controllable color theming and extensive support for user-configurable interaction preferences, it is easy to tune the console to fit your style (and your eyesight). MIO Console also adds support for standard UI gestures including drag-and-drop for inserts and multi-strip control swiping.

  • MIO Console provides the UI to control the mkIV Mixer. This mixing engine is a full blown mixing console - not a mere interface monitor mixer. It features multi-bus mixing, arbitrary routing, input and output multing, zero-latency hardware plug-ins, surround support, and headamp control. The Mixer removes the limits that other interfaces have by providing:
  • Up to 128 channels of input (@192k)
  • Up to 64 (mono) busses (@192k)
  • Mix busses that span all the hardware in your MH system
  • Mix and panning support from mono up to 7.1
  • Automatic routing to the computer
  • Cascade assignment of inputs, sends, busses and plug-ins
  • Instantiating plug-ins and graphs with presets
  • Dragging plug-in inserts within the mixer (including drag-copy)
  • Unlimited Parameter Link Groups
  • Unlimited DCAs
  • Unlimited Mute Groups
  • Hardware polarity invert
  • On-strip headamp control
  • Pre- and post-insert direct outs
  • Hardware I/O inserts
  • Latency compensated buss-to-buss summing
  • Support for automatic input switching and punch-in with Session
  • Support for automatic Session I/O routing
  • Comprehensive metering
  • Optional non-destructive AFL/PFL soloing
  • Hard Mutes
  • Fully configurable Main, Aux and Group busses (up to a total of 64 mono busses)
  • Aux sends directly on mixer strips
  • Flipping Auxes onto the primary mix surface (in both the UI and on hardware control surfaces)

These features taken together unlock mixing workflows specifically targeting live and zero-latency cue mixing during tracking as well as enabling you to record and mix with Session as a dedicated solution.

MHLink - All Together Now…

MHLink redefines audio interconnect technology.

It supports up to 128 channels at 32-bit/192k, bidirectionally, on each port.

MHLink intelligently manages low-jitter audio clock distribution, high-bandwidth audio streaming and system control data all on a single lightweight, inexpensive, industry-standard Cat5/5e Ethernet cable.

The MHLink transport automatically unifies all connected devices into one super unit — which maximizes your audio performance while minimizing complexity.

Expanding your system is as simple as chaining another unit.

Step 1: Plug another unit to the end of the chain.
Step 2: There is no step 2.

MHLink devices can be added dynamically without interrupting running audio streams. All I/O ports of new devices are automatically available for routing within seconds of being connected.

MHLink key features:

  • There is no latency offset between the individual devices. With MHLink, the maximum transport latency between units is 16 microseconds, regardless of whether two units are directly connected or there are 16 additional units in between.
  • Up to 100 meter MHLink Cables — Say goodbye to your expensive, heavy, noisy analog snakes. Place your Metric Halo setup where it is best positioned and remove hundreds of meters of analog audio cable. Easily connect your Metric Halo unit with commodity Cat5/5e cable with up to 100 meters of cable length per MHLink connection.
  • Split systems — With up to 100 meters of cable between units, put your primary system on stage (or your live room) and your monitor box at FOH (or your control room). MHLink adds no latency and provides a common clock; you can even use existing installed wiring plants for tie-lines.
  • Integrated daisy-chain support — No need for the added expense and complexity of Ethernet switches.
  • MHLink uses true locking connectors to provide security from cables getting snagged and disconnected at the worst possible time.
  • MHLink is transformer coupled at each port so all your MHLink connections are galvanically isolated. This makes operation extremely safe while also protecting your recording system against electrical interference and the introduction of data-path ground loops.
  • Integrated, Automatic Clocking — No need for word-clock or any other digital interface to transparently lock multiple MH Linked units’ clocks.
  • Standards-compliance provides support for both direct connection and switched connection to computers via MHLink.

Instantly Scalable

A unique feature of MHLink is that all Metric Halo interfaces work as well as a group as they do individually. Mix and match ULN-8 mkIV with other 3d units to create a system that meets your needs for track count and preamp power.

Adding a unit to the system automatically increases the DSP power of the system, so that your DSP always scales with your I/O.

Break your system up for small gigs when playing out or add the units of your mates to build a huge system when required - just click to connect!


Every mkIV unit includes an industry standard USB-C port that provides a device port featuring 3 interface endpoints:

  • USB Audio Class 2
  • USB MIDI Class
  • MIO Control Class

The Audio Class and MIDI Class endpoints support industry standard protocols and allow the mkIV to be used with the built-in drivers of any USB host that supports the standard classes.

You can transport audio and MIDI to and from computers running macOS, Windows 10 & 11, or Linux without installing a custom driver.

You can transport audio and MIDI to and from mobile devices (and embedded devices) that don't allow the installation of custom drivers, as long as the devices provide built-in Audio and/or MIDI class support. At present iOS devices (including iPhone and iPad), Android devices (phones and tablets) and AKAI MPC have the appropriate class drivers included.

MIOConsole3d also controls the unit over USB so you can connect your computer with one cable.


Have you ever wanted to connect an iPad to your main studio system? How about dedicating an older computer you have laying around to running a VI or a Sampler? What about when a client or collaborator comes in with their laptop and wants to run audio into your system? With mkIV and SCP, you can just connect any of these devices right into your system without having to add another interface just for that purpose.

mkIV supports explicit routing to and from the USB connector on any unit in the MHLink chain. When used in this way the USB ports are referred to as Satellite Computer Ports.

This feature allows you to integrate audio from multiple USB host devices (computers, phones, tablets, MPCs, etc.) without having to purchase additional interfaces. It automatically keeps your devices synchronized with your system and provides device to device routing as well as integrated mixing and processing.

You can connect a sampler running on a another computer and directly mix its outputs with the rest of your sources. You route directly between computers/devices or mult signals to multiple computers/devices - so you can set up a computer or an iPad as an effects rack or backup recorder.

You can integrate the output of multiple iOS instruments into your MHLink Mixer via the direct digital link and you can record real-time performances by routing them to your main recording computer.

You can use the SCP functionality to integrate multiple computers (or iOS devices) into your MHLink mixing engine. Each USB port is available for connection with a USB audio host. The SCP USB source and destination categories in the routing selector popups allow you to select explicit USB channels to route to and from.

To use a USB port as an SCP port, simply connect the device to one of the USB ports on one of the units in your MHLink chain. Then on the device, select the USB interface of the connected 3d unit as the audio interface for the device, signal processing software or DAW.

It’s as simple as that.

System Requirements


Any Mac that supports macOS 10.9.x or newer with a 64-bit Intel or Apple Silicon Processor
One of:

  • USB port
  • Built-in Gigabit Ethernet Port
  • Thunderbolt Gigabit Ethernet Adapter
  • Thunderbolt Dock with Gigabit Ethernet Adapter
  • USB3 to Gigabit Ethernet Adapter
  • PCIe Gigabit Ethernet Card


  • macOS 10.9.x or newer required


All CoreAudio compliant software is compatible with ULN-8 mkIV, including:

  • Cubase
  • Digital Performer
  • GarageBand
  • iTunes
  • Abelton Live
  • Logic
  • Studio One
  • Bitwig
  • Nuendo
  • Resolve
  • MixBus 32c
  • soundBlade
  • Pro Tools
  • Final Cut Pro
  • and hundreds more…

What’s Included in the Package

Each ULN-8 mkIV includes the following items:

  • One ULN-8 mkIV unit
  • One IEC Power Cord appropriate for your area
  • One 19-volt 60-watt world-ready external power supply
  • One 2’ and One 10’ CAT5e Ethernet Cable
  • One USB-A to USB-C Cable
  • Two Rack Ears with fasteners
  • Rubber feet
  • Configuration jumpers
  • Warranty/Registration Card

UPC: 832081000705

Reviews: Metric Halo ULN-8 mkIV Audio Interface

There are currently no product reviews.