First Listen: Meridian Prime Headphone Amplifier USB/DAC

Headphone amps and amp/DACs
First Listen: Meridian Prime Headphone Amplifier USB/DAC

The last year or two has seen the engineers of Meridian Audio as busy as elves in Santa’s Workshop. First there was Explorer, a pocketable USB streamer for dedicated headphone wearers, next there was Director–larger, input laden and oriented towards home system users–from servers to Apple TV. BTW-I’ll be reviewing the $699 Director in TAS Issue 240, coming soon.

But by far, the final jewel in the crown is the just-released Prime-a premium analog headphone amplifier with built-in USB/DAC connectivity. It's price is $2000 so it's playing against some heady competition. However Meridian considers it a “reference” product, and lucky me, I’ve been afforded an early and hurried listen.

First the particulars: Prime includes dual high-quality oscillators, based on those found in Meridian’s top-of-the-line Reference Series components. It can handle any standard sample rate up to 192kHz with minimal jitter. The Prime Headphone Amplifier’s USB input automatically upsamples 44.1/48kHz sources to 88.2/96kHz prior to the DAC, using Meridian’s special apodising filter. Of particular interest is Meridian’s proprietary Analogue Spatial Processing ASP technology  which in Meridian’s words, is geared “to deliver more immersive, authentic sound to any headphones… providing a more natural spatial soundstage that’s more like listening on loudspeakers.” More on this later.

The USB section of Prime is a true Class 2 USB audio powered entirely from the interface–no additional power supply required (more on that later). Meridian points out that since the USB conversion system is interface powered, when it is disconnected, “all digital circuitry in the unit is deactivated”, ensuring that no digital noise is introduced into the analog circuitry.

The look is classic, understated Meridian, or more accurately miniaturized classic Meridian.  Designed by co-founder Allen Boothroyd  comparisons to the iconic G-Series and the original 100 series are obvious. The enclosure is a dual-skinned design of interlocking extrusions, for exemplary isolation of the delicate circuitry. And no screws–the box is opened by a hidden magnetic release mechanism. The volume control uses a flexible coupling link from the shaft of the potentiometer to the rear of the enclosure minimizing microphonics from mechanical noise. LED pinlights on the front panel illuminate to indicate input selection and sampling rate as well as ASP.

Designed for multiple headphone users the front panel has dual ¼** input jacks and a mini 3.5mm jack for ear phones and in-ear devices. The stated commitment is any headphone, any load, including separately wired L/R channels. Parts selection is also prime and includes for example, an Alps volume pot, and Nichicon caps. The back panel houses a USB input, a pair of gold plated, RCA inputs (LP sources? By all means.) and a mini jack input for personal players. There’s also a set of preamp outputs to drive an amplifier or active loudspeakers to further expands connectivity options. However, when headphone-only listening is preferred a mere press of the power button until it glows green will disable the circuitry driving the preamp output–a cool function that gives Prime that additional purist edge over some of its competition.

I haven’t done a comprehensive survey of headphone amps like some of our staffers but in terms of the criteria that I listen for in any amp, transparency, noise, dynamics and the ability to get me out of my head and into the music, Prime is well, prime. Using AKG K501 headphones and the Cardas EM5813 earphones the perceived noise floor is vanishingly low which aides in the recovery of low level dynamics and casts the entire dynamic and transient envelope in a more favorable light. The amp is pacey,  and alive with timbre detail and clean, clean image definition. In my brief time with the Prime I was all over the place with my musical selections. From classic James Taylor and Carole King high-res tracks from HD Tracks to ripped CDs of various genres and Rachmaninov’s Symphonic Dances from the  Reference Recordings HRx disc

As for ASP I was expecting something akin to the audio whoopee cushion-in other word, a bit of fun but, not for long. What I encountered was something vastly more measured. The effect is subtle. Actually there are two modes–flat and a (very subtle) bass boost. Either way, there are no weird shifts in tonal balance that would create suspicions of EQ voodoo. The AKGs still sounded a little lean, the Cardas remained a bit lush and warmed over. Rather it’s as if the instrumentalists and vocalists are suddenly playing on the same stage, sharing the same space and ambience. The center firms up and the world of the recording is no longer flat. It’s almost as if the recording has suddenly developed a third track, like a center channel only more subtle. After all this is the company with a deep algorithmic tool box-the same firm that developed Trifield process many years ago. Just sayin’.

ASP reproduces music with more presence and more dimension and seems to enable the music to relax and shift away from the extreme right & left ear position and settle naturally on a more familiar soundstage. It’s particularly impressive reproducing the soundspace of well recorded orchestra but pop vocal images seem to beef up up with physical weight and depth. They are simply more believable. It doesn't completely free the sound from your head but for this listener it was rare that I switched off the ASP except to remind myself why I didn’t want to listen to music without it.

And That’s Not All, Folks!
Prime is powered by the included wall-mounted supply but in early December there will be another option for the uncompromising among us–the Prime Power Supply will be available for an additional $1250. Sporting the same footprint as the Prime headphone amplifier, using this external power supply means that AC noise is kept well away from the pure analog stages of the headphone amplifier. In a phone conversation with Ken Forsythe, Director of Product Management I asked him what to expect from the Prime PS. He told me that with the external PS installed the noise floor drops another 5dB thanks in large degree to the massive 2lb toroid transformer. Far and away the coolest feature of the Prime Power Supply is  a USB thru-put which strips the 5V power from the PC and adds it to the PS. Forsythe feels the sonic improvement to soundstage and openness is impressive and should appeal to customers seeking “that last 5%  in over-the-top performance”.

All in all, a seemingly impressive effort that covers all the bases. However, I think some further, more casual listening will be required before I can arrive at a final conclusion. I hope they don't want this thing back before the holidays. 

Prime Specs
Suitable for impedances between 16 Ohm & 1 kOhm
Dimensions: 6.3” x 2.0” x  5.9”
Weight: 2 lbs
Price: $2000

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