Find out more

Pristine sound.
Everywhere YOU GO.

Enjoy 3 months’ complimentary subscription to
TIDAL with any Meridian product purchased.

Find out more


The HD621 is a pitch-perfect problem solver. HDMI connectors are a common sight on high-definition equipment, helpfully carrying audio and video signals. But digital video signals can prove detrimental to sound quality – so the HD621 cleverly solves this problem by extracting the audio signal from the HDMI input and routing it through the high-tech audio processing of a Meridian system.


The result is a significant boost in your system’s sound quality. Not only that, the HD621 also ensures that sound is always in perfect synchronisation with the picture – no more watching the actor’s lips move and hearing the sound follow a moment after. With space for up to six HDMI-equipped devices, the HD621 design matches the Meridian line and is available in free-standing and rack-mount versions. Problem solved.

Pristine sound.
Everywhere YOU GO.

Enjoy 3 months’ complimentary subscription to
TIDAL with any Meridian product purchased.

Find out more

Experience Meridian for yourself.
Hear the difference

product video

The beauty of the machine

Discover how more than 35 years of pioneering innovation led to the perfect balance of form and function.

Watch film



  • Gallery Item 0
  • Gallery Item 1
  • Gallery Item 2

Experience Meridian for yourself.
Hear the difference


Signature features

Six-input HDMI switch.

HDMI video output.

Extracts up to eight channels of high-resolution audio from the HDMI data stream, supplying them to separate audio-only outputs.

Connects HDMI audio direct to a Meridian system.

Smartlink coaxial digital audio output (up to 8 channels).

Multichannel Meridian High Resolution (MMHR): balanced digital audio output via RJ45/Cat 5 cable (up to 8 channels).

Up- and down-sampling of digital audio.

Audio FIFO buffering and resolution enhancement improves PCM audio received via HDMI.

Lip-sync control compensates for latency resulting from external digital video processing.

Keeps HDMI video signals away from your audio equipment, minimising signal degradation.

The HD621 performs up- and down-sampling of digital audio and includes Meridian's unique apodising system to ensure the very best sound from today’s varied sources. Meridian’s highest-performance FIFO buffering technology removes HDMI jitter, consistently delivering a significant improvement in audio quality from all your HDMI sources.

FIFO Buffering FIFO Buffering
Each sample of a digital recording must remain evenly spaced in time. Unfortunately, timing can vary, especially when reading discs. This is “jitter”, degrading music's sense of space and diminishing realism. Meridian's multiple “First In, First Out” buffering system minimises jitter, ensuring perfect timing and improved clarity. You enjoy a clearer feeling of the instruments and their interrelationship.
Meridian Apodising Filter Meridian Apodising Filter
Filters are critical in digital audio. Commonly they introduce distortion and harshness because of "pre-ringing". Early digital recordings suffer from harshness too, due to primitive filters. After painstaking research, Meridian developed a special filter that avoids pre-ringing, so it can be steeper, cleaning up the effects of early filters. The result: a better, cleaner sound from recordings old and new.
Meridian High Resolution (MHR) Meridian High Resolution (MHR)
MHR was the first approved encryption method for transferring high definition digital audio between components. Previously, it had to be in the analogue domain, reducing quality. MHR allows secure movement of high resolution digital audio within a Meridian system, without compromise, improving quality by reducing cyclic repetition.

Experience Meridian for yourself.
Hear the difference



The Meridian HD621 HDMI Audio Processor is the vital link between your Meridian system and the latest sources, such as Blu-ray Disc®, satellite/TV receivers and gaming consoles with HDMI outputs.

Many components supply both audio and video via the same HDMI cable, which compromises quality. The HD621 separates the HDMI signal from up to six sources into its audio and video elements, maximising the audio quality and delivering it to your Meridian system free of video pollution, while the video content is fed direct to the display via a single cable, eliminating additional switching.

The HD621 integrates multiple HDMI sources – including those with 3D video – seamlessly into your Meridian system. So seamlessly, in fact, there’s even a programmable lip-sync delay to be sure sound and picture remain in perfect synchronisation – one of the most important details in a quality video experience.

If you want to expand your Meridian experience to include the latest audio and video components, the HD621 forms the vital link.

Supports both 2D and 3D video formats.

A perfect partner for one of Meridian's Surround Sound Processors such as the G65 or 861, enabling you to input and decode HDMI audio sources.


Power input (IEC connector)

DB9M Sub RS232 serial connector

BNC and DIN Meridian Comms

Six HDMI input sockets

HDMI output

8-channel MMHR digital audio out (RJ45)

8-channel coax digital audio out (4 x phono)


Power LED

6 x HDMI Input LEDs (selected input lights)


1U 19in rack mounting or free-standing


Internal universal power supply, 100–250V AC

Maximum power consumption: 40W


4.5kg (10lbs)


If you own this product and have a question you’d like us to answer, please visit our dedicated support area. Get product support