WORDS AND MUSIC

REVIEW: Meridian Prime Headphone Amplifier – so much more than the name suggests

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The new headphone amp from Meridian is its most ambitious personal audio product so far, with analogue and digital inputs, processing to get the sound out of your head and the ability to be used as a preamp

And then there were three: on the heels of Meridian’s Explorer DAC/headphone amp and recently-launched Director DAC comes the new Meridian Prime Headphone Amplifier, the company’s most ambitious to date.

With both analogue and digital inputs, and the ability to function as a dedicated headphone amp or even a preamplifier straight into a power amp or active speakers, the Prime will sell for £1200 when it goes on sale in December, with the option of a dedicated Meridian Prime Power Supply (below) at £800 to replace the plugtop PSU supplied as standard.

The Prime Power Supply uses a handbuilt toroidal transformer: a high-mass, low-profile, low magnetic field design. It has an integral magnetic shield, and is mounted on a metal plate to shield electronics from noise. The PPS uses six extremely low noise regulators, and as well as providing 5V 1A power for devices such as the Prime Headphone Amplifier, for which it has a USB pass-through arrangement with a Type B input and Type A output, it also has five 12V 500mA outputs on mini-DIN sockets for other Meridian components, as you can see below.

I haven’t been able to test the Prime with its hotrodded power supply: at the time the review unit of the Headphone Amplifier was delivered, in packaging slightly obviously explained not to be the finished article – plain brown box and lots of foam –, there was only one pre-production Prime Power Supply so far released into the wild, and it hadn’t been released in this direction!

Anyway, back to the Prime Headphone Amplifier, and rather unusually these days, it has only one digital input, on a Mini-USB socket, along with two analogue ins – one on a pair of RCA phono sockets, the other on a 3.5mm stereo socket. Front panel headphone outputs are provided on two 6.3mm sockets and one 3.5mm, so no need for fiddling around with adapters whichever kind of plug is on the end of your cable.

Look past that simple litany of sockets, pausing only to wonder whether the odd S/PDIF connection – on either an electrical or optical connection – might have been handy, and you’ll begin to realise that this isn’t actually a DAC with a built-in headphone amp, but primarily a headphone amp with the added benefit of a DAC able to take audio from a computer.

Mind you, I guess the clue is in the name of the product…

Inside story
Not that this means the digital side of the device is in any way a makeweight – well, you wouldn’t expect it to be, given how deeply steeped Meridian is in all things digital. The USB input is a true asynchronous type, able to handle signals at up to 192kHz sampling rate, and upsample 44.1kHz or 48kHz signals to 88.2 or 96kHz respectively.

It uses high-quality oscillators based on those used in the company’s Reference Series digital products – handy, given that the Prime Headphone Amplifier looks like one of those units in miniature – and has the company’s Meridian Resolution Enhancement, including the proprietary apodizing filter, to increase the quality of the digital signal being fed to the digital-to-analogue conversion.

Used with a USB input, that section of the Prime is powered from the computer; unplug the USB hook-up to use the Prime as a headphone amp with analogue sources, and the entire digital section is shut down to avoid any chance of noise being introduced into the analogue circuitry.

You can also turn off the preamp-level outputs to make the most of the sound through your headphones of choice: press and hold the power button and it turns green as the Prime enters headphone-only mode.

Even the headphone outputs provided are different, and not just in size: although all are active at the same simultaneously, the 3.5mm socket has an impedance of around 2Ω, suitable for most portable-friendly ‘phones, while the two 6.3mm sockets have a much lower impedance of about 3mΩ, which is better suited to high-quality home-use headphones.

Whichever headphone output you use, Meridian’s Analogue Spatial Processing can be switched in if required: it’s designed to give a listening experience more akin to music on speakers. The idea is that, whereas headphones deliver left-channel audio only to the left ear and right to right, when listening to speakers each ear hears sound from both speakers; the ASP system is available in two ‘strengths’ to replicate this effect, and all its processing is done in the analogue domain.

I mentioned the styling of the Prime earlier, and as you might expect from this company, there’s more to it than just looks: the work of Allen Boothroyd (the industrial design counterpart to Meridian’s electronics designer Bob Stuart – the two co-founded the company), the casework is assembled from interlocking dual-skinned extrusions, and is held together without screws, a magnetic release mechanism allowing it to be opened for servicing.

Or at least apparently so: I have to admit I couldn’t fathom out how to get inside it, but then I was always rubbish at Rubik’s Cubes, too!

And the Prime’s tiny, at just 16cm wide: it may draw on technology from the company’s Reference Series, but an 800-series product absolutely dwarfs it!

Even that volume control is unusual, with a flexible coupling linking the knob to the volume potentiometer within, to ensure external vibrations don’t get through to the sensitive audio circuitry.

Question is, how does it sound? Well, I’ve been playing for just over a week now, using the Meridian with a range of headphones including a pair of monster old Sony MDR-CD3000 ‘phones from way back when – they were a rather more affordable version of the MDR-R1, beautifully made but in slightly less exotic materials, and still some of the best-sounding headphones I have ever used –, B&W’s P3s and a pair of Bang & Olufsen BeoPlay H6 Agave Greens.

In each case the Prime made the headphones sound as good as I have ever heard them, including when they were used with the fine headphone stage in the Naim DAC-V1, whether I tried it fed directly from the line-out on my Naim NDS network player or fed via USB from my MacBook Air.

In fact, to see just how much the Meridian was bringing to the party, I even tried it connected to the line-out on the Fiio X3 portable music player, allowing it to prove not only how good a headphone amplifier it is, but also just how well the little Fiio delivers high-resolution music when it’s not being asked to work hard to drive your headphones.

Analogue Spatial Processing
The Analogue Spatial Processing? We-e-e-ell… I can hear what it’s trying to do, and yes it definitely makes a difference when switched in, reducing that slightly claustrophobic sensation one can get with some headphones in its first position, and giving a very open and spacious sound at its second setting.

However, the effect varies fairly wildly between recordings, and what can sound rather appealing with one album can get a bit too weird and phasey with another – or in some cases from one track on an album to another –, especially in using the ‘ii’ setting.

My worry is that I’d be constantly switching between the settings while playing music, and would be spending too much time flicking between them to give my full attention to what was being played. No, let’s clarify: I did exactly that, to the point that it was driving me slightly crackers with all the ‘Oh, that’s good – ah, hang on…’.

As a consequence, I’ve left the Prime’s ASP on its ‘i’ position, which is relatively subtle in its effect, for most of the time I’ve spent with the amp to date, only resorting to changing the setting in the odd ‘I wonder what it’ll do to this’ moment.

The simple version is that the Analogue Spatial Processing works best with a really good recording, where it can give a slightly uncanny ‘out of the head’ soundstage seemingly floating in front of you in best ‘Help me, Obi Wan Kenobi, you’re my only hope’-style.

With poor recordings or streams, such as internet radio, BBC podcasts or even some volume-levelled (for which read compressed) sources such as Spotify, the results are – well, let’s say somewhat less predictable. Things can get get a bit swimmy and unusual inbetween the ears.

What’s in no doubt is that the Prime sounds noticeably different through its headphone outputs when the preamp section is on or off, gaining extra transparency through its headphone outputs when running in headphone-only mode; click it back over to running preouts and headphones in parallel, and there’s just the slightest loss of focus. Which, given how crisp, clean and powerful the Meridian sounds through headphones at its best, is a loss worth avoiding.

However, it does also work very well as a preamplifier when required: I ran it straight into a pair of mono bloc amps and then on to my speakers, and it was remarkably crisp, clean and powerful-sounding whether connected to the computer or to analogue sources.

Buy one, get two free
So we’re really back to the name of the product, and maybe the Meridian Prime Headphone Amplifier’s title isn’t quite as self-explanatory as at first it seems. In fact, this little product is actually a headphone amplifier, an upsampling asynchronous DAC and an analogue preamplifier, and it can do any of those jobs separately, or all at the same time. And whether doing one thing or all three, it performs equally well. Or rather extremely well.

Put like that, what at first might seem to be a rather steep price for this compact little box seems to make perfect sense. After all, you do get quite a lot for your money…

Meridian Prime Headphone Amplifier
£1200
Inputs Asynchronous USB, analogue (on 3.5mm stereo socket and one pair of RCA phonos)
Outputs Headphones (on two 6.3mm and one 3.5mm sockets), preouts
File formats Up to 24-bit/192kHz, with 44.1kHz and 48kHz signals upsampled to 88.2kHz and 96kHz respectively
Power supply Plugtop mains adapter supplied; Meridian Prime Power Supply £800 option
Dimensions (WxHxD) 16x5x18cm (depth includes volume control and sockets)
www.meridian-audio.com

Written by Andrew Everard

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