Meridian Audio is on a roll this year releasing the Explorer, Director, and now the Prime. All three are headphone amplifiers but the Prime is another league. In addition to asynchronous USB input for sample rates up through 24 bit / 192 kHz PCM like the Explorer and Director, the Prime can function as the center of both digital and analog audio systems. Featuring both digital and analog inputs that don’t cross paths internally the Prime is much more of a foundation piece upon which to build a high quality audio system than solely a headphone amplifier as its name suggests. The build quality and the look of the Prime are terrific. The Prime exudes both a pride in craftsmanship from Meridian and no doubt a pride of ownership for the consumer. I envision the Prime quarterbacking many an office audio system in the near future driving both headphones and powered loudspeakers. The Prime is fairly small but it isn’t portable. Listeners enjoying the Prime at work will likely want a matching unit for the house once they hear what Meridian’s Analogue Spatial Processing if capable of delivering via the headphone outputs. Listening to plain in-the-head audio just doesn’t cut it any longer. Whats more, add the Meridian Prime Power Supply to the mix and it’s primetime for audio enthusiasts everywhere.[PRBREAK][/PRBREAK]
Sights and Sounds of the Meridian Prime Headphone Amplifier
In October at the CEDIA show in Denver I talked to Meridian’s Ken Forsythe about the upcoming Prime Headphone Amp. I thought the unit would be similar to the Explorer and Director with a couple nicer features. Either Ken was holding back all the good information or I wasn’t listening very well because I was pleasantly surprised by both the sights and sounds of the Prime. It’s impossible to overlook the new form factor compared to the other Meridian products in this category. The Prime is perfect for nearly any desktop. I’ve had it sitting on my desk for a couple weeks. That’s much longer than most components last on my desk. Components usually get in the way because they are too large. Or, they are too small and get shoved off the back of my desk or under papers accidentally. The Prime fits on the base under my Apple Cinema Display but it’s a hair to large to look like it was made for such positioning once the cables are connected.
The mostly metal enclosure is made of dual skinned interlocking extrusions that help keep outside interference on the outside of the Prime. The Prime is screwless. OK, the only visible screws are on the back near the in/outputs. The chassis is opened with a hidden magnetic release mechanism that I’ve yet to locate. I have some guesses, but I’d rather not blemish this fine looking review sample. According to Meridian, “Even the curve on the volume knob was carefully chosen.” My one gripe with the Prime is the curve on the volume knob. It’s slippery and doesn’t feel luxurious between one’s fingers. For example, as I type this review I can reach over to my left and adjust the Prime’s volume. To do this I make the A-OK gesture with my thumb and forefinger before grabbing the volume knob. Upon contact with the knob my grip is less than solid and my fingers either slip around the knob or down the point of the knob. This is certainly not a showstopper, but it’s something that bugs me frequently. The rest of the external design is really nice. Meridian’s chosen white LED lights in the center of the power button and on the front face are elegant.
The Meridian Prime features several items that are critical to its great sound quality. Perhaps most interesting to headphone and specification geeks is the impedance of the headphone sockets. The front panel mini (3.5mm) jack has an impedance of around 2Ω. The quarter inch jacks, of which there are two, have an impedance around 3mΩ. That’s three milliohms or three one thousandths of an ohm. The Prime can drive nearly all dynamic headphones on the market including those requiring separate right and left cables. Thus the reason why the Prime as dual quarter inch headphone outputs.Sure some people may listen to headphone with their spouses, but c’mon two 1/4 inch jacks is all about sound quality not sharing. When listening to only headphones it’s possible to dibble the analog preamplifier output by holding down the power button until all the front panel lights illuminate. Releasing the button then displays a green light in the center of the power button to indicate the Prime is in headphone only mode.
Contributing to the Prime’s excellent sonic performance is its class 2 asynchronous USB digital input. Much of the Prime’s performance revolves around this USB input from power, to filtering, to upsampling. The USB interface is capable of receiving PCM audio up through 24 bit / 192 kHz. Meridian does not support native DSD playback. I played much of my DSD content using JRiver Media Center for Mac and using its on-the-fly DSD to PCM conversion. There is strong engineering support that this method of DSD playback may be equal to or better than native DSD. That’s a topic for another day to say the least. Prime features dual fixed crystal oscillators for 44.1 kHz and 48 kHz based material. Both 44.1 kHz and 48 kHz audio entering through the mini-B USB input is upsampled by a factor of two to 88.2 kHz or 96 kHz. This upsampling takes place before the DAC using Meridian’s much lauded apodising filter. The marketing term for all this is Meridian resolution enhancement technology. The USB interface powers the complete USB section of the Prime. In other words, the computer send power from its USB bus over the USB cable to power the USB section. Based on my experience this is the most popular way to power USB interfaces in high end audio. What may be overlooked is the fact the Prime’s digital circuitry is completely deactivated when the USB interface is disconnected. Without power there can be no digital noise entering the analog circuitry. Readers seeking additional digital inputs such as TosLink of coaxial S/PDIF should consider Meridian’s Director product. I highly recommend pairing down to a single USB interface if possible because the Prime is that much better than the Director. I don’t see the single digital input of the Prime as a showstopper. In fact, I struggle to find reasons why I’d want another input for my daily use.
Listening through the Prime with my Sennheiser HD600 headphones connected to both the 3.5mm and 1/4 inch outputs was a real treat. The Prime’s sound quality is impressive. I’ve been on a Jack Johnson kick lately an enjoyed listening to all his albums with this combination. I sent audio out to the Prime from my MacBook Pro with Retina display running OS X Mavericks (10.9) in exclusive and integer modes with JRiver Media Center v19. The acoustic guitar on Jack’s In Between Dreams album sounded very authentic through the Prime. The sound as a whole wasn’t fatiguing and enabled me to listen for hours without even thinking about the fact I was listening through headphones. The last time I heard Jack’s vocals sound better was through the $10,000 combination of Stax 009 electrostatic headphones and a Head Amp Blue Hawaii amplifier. The Prime easily drove my HD600 headphones to deliver the deep bass notes and great percussion on Keith Richards’ Words of Wonder from his solo Main Offender album. Words of Wonder is a great song that can sound really fabulous through the right system. The bass was very clear with delineation between each note. The percussion had really nice air surrounding each tap, bang, smack, or whack of the instruments. I also listened to Shelby Lynne’s Just A Little Lovin’ album a few times through the Meridian / Sennheiser combo. On the title track the soft but ever present bass lines can be heard clearly without cranking up the volume like one was putting on a HiFi demonstration. This is great music and I listen like a normal human being, at one volume for the entire track. On a great system the bass on this track can be heard nicely at low volumes. This was the case through the Meridian Prime. Similarly to the Keith Richards’ track, Just A Little Lovin’ features great percussion near the end that should give the listener a sense of the recording space when reproduced well. The Prime excelled at percussion reproduction on this and all the other tracks I played.
Raising Performance Another Two Levels
Throughout the review period there was two items that raised the Prime’s performance unequivocally. The first is what Meridian calls Analogue Spatial Processing (ASP). The reason for ASP is simple. When listening to music through loudspeakers both left and right ears hear the audio signal from both left and right speakers. When listening through headphones however the experience is cut off by one’s head. Each ear only hears the audio from the headphone driver in, on , or around that specific ear. The sound is normal for many people who don’t listen to loudspeakers often and people who’ve never experienced spatial processing. Meridian’s effort to elevate the in-the-head audio problem, Analogue Spatial Processing, is done entirely in the analog domain. That fact should please the diehard analog audiophiles who despise digital signal processing (DSP). Meridian’s ASP can be enabled in two different modes, that emulate listening to loudspeakers in a room, through an appropriate blend of left and right channels and differing amounts of delay similar to the delay one hears from left ear to right ear and vice versa when listening to loudspeakers. Setting 0 is a complete bypass of the ASP. The difference between setting i and ii is the amount of blend and delay that emulates differing loudspeaker angles. The ASP button is located to the left of the volume knob enabling one to switch from bypass to i to ii in a fraction of a second. Readers who like to A/B components or configuration changes can indulge themselves for days if needed.
Analogue Spatial Processing isn’t for everyone and isn’t even for every track for those of us who really like the technology. Several headphone amp manufacturers have tried different implementations of spatial processing in both the digital and analog domains over the years. Most were met with resistance from the audiophile market. Thus, the reason there are so few solutions available. Meridian’s ASP, when used at the right time, is one implementation I can’t live without. Many of my favorite rock recordings from band such as Pearl Jam and Foo Fighters didn’t sound better with ASP enabled. The real difference could be heard when listening to albums from artists such as Chet Baker, Miles Davis, and John Coltrane. One of my favorite Coltrane albums is Standard Coltrane released by Analogue Productions. The first track Don't Take Your Love from Me benefits so much from Meridian’s ASP that I really hate to go back to normal headphone listening. On this track John Coltrane’s sax is solidly in the left channel while the bass and drums are solidly in the right channel. Listening through loudspeakers in a regular room the track sounds terrific. Listening through a regular headphone amp the track is disjointed without any fluidity even though Coltrane’s sax is lush and smooth. Enabling ASP level i on the Prime brings this track back to life and enabled one to listen to the great music and great musicians without thinking about an incoherent sound separated by one’s own head. The Analogue Productions release of Chet Baker’s Chet album sounds much the same with and without Meridian’s ASP. The first track Alone Together is another of my favorite tracks of all time. listening with ASP set to level i was a wonderful experience. I toggled between level i and ii countless times during the review period and settled on i as my preferred ASP setting. Listening to the newest version of Miles Davis’ Kind of Blue from HDtracks at 24/192 was equally as enjoyable but slightly different. On the track Blue In Green Miles’ trumpet can be heard in both ears even with ASP disabled. The ASP really helped with the surrounding instruments especially Bill Evans’ piano and Jimmy Cobb’s drums. ASP brought everything together in a cohesive image that placed the music in front of my forehead rather than stuck between my ears. Based on my experience with the Meridian Prime’s ASP I’m a firm believer that spatial processing can be implemented naturally. I want it in all my headphone amplifiers.
The second item that raised the Prime’s performance unequivocally was the Prime Power Supply (PPS). The PPS has yet to be released. The version I received was a preproduction model to be used for preview only. The production PPS will ship in December 2013 at an MSRP of $1,250. Once I put the PPS in place there was no going back. The Prime Power Supply, hand made near Cambridge, UK just like the Prime Headphone Amp, addresses not only the age old dirty AC power issue, but the newer issue of dirty USB power flowing from the computer playback system. The PPS has six extremely low noise linear regulators with pre-regulators for both 12V and 5V USB outputs. The high current PPS is a low noise linear supply based on the work Meridian has done for its 800 Reference Series components. Clean power and removal of power supply noise from near the sensitive analog circuitry has been encouraged for decades in this hobby. In the last few years computer audiophiles have recognized the need to clean up the power sent from their computers to their DACs via the USB bus. Several methods including separate USB audio cards, battery supplies, and cutting off USB power entirely when possible have been used by audio enthusiasts including many Computer Audiophile readers. Meridian has also recognized this USB bus power weakness. To combat the issue Meridian implemented a USB power pass-through in the Prime Power Supply. From a computer audio perspective this is one of the best things to happen since asynchronous USB. The PPS USB pass-through accepts the USB output from a computer, cleans it up, and sends it on to the Prime Headphone Amp. That’s the layman’s description. In technical terms the computer is connected to the PPS with a standard USB A to USB B cable. The PPS routes the USB signal through a high-efficiency low-dropout (LDO) linear regulator with less than 5μVrms output noise in the 10 – 100kHz range. The USB 5V signal is then routed out of the PPS on a USB A port with low noise power to feed the Prime Headphone Amp via its USB mini-B input. I connected the PPS to my laptop with a Wire World Silver Starlight USB cable and connected the PPS to the Prime amp with a Wire World Silver Starlight featuring a mini-B USB termination. Meridian supplies a seven inch USB A to USB mini-B cable to connect the PPS to the Prime Headphone Amp. The increased audio performance from the Prime Power Supply is fantastic, but equally as important for computer audiophiles is Meridian’s recognition of the USB power issue. Meridian is a solid engineering based company that doesn’t sell snake oil with hocus pocus and smoke and mirrors. The USB power pass-through in the Prime Power Supply isn’t a solution looking for a problem. It addresses a real issue that has heretofore only been addressed by few and has incorrectly been viewed by some enthusiasts as a non-issue as long as the bits reach the DAC unchanged.
In its preproduction state I can’t really knock the PPS for anything. I can however offer Meridian one suggestion on a feature I’d like to see in the final production version. This may actually have more to do with the Prime Headphone Amp than that PPS, but it doesn’t become an “issue” until the PHA is connected to the PPS. I would really like the Prime Headphone Amp to feature a Last State power option. What I mean is this, when both the PHA and the PPS are powered on, then the PPS is turned off, then the PPS is turned back on the PHA should go back to its last state. If the PHA was off when the PPS was turned off the PHA should remain off when the PPS is powered back on. If the PHA was on when the PPS was turned off the PHA should automatically come back on when the PPS is powered on. Computers have had this option for decades. When power is lost to a PC it can remain off, turn on, or resume its last state (the state it was in when power was lost). Maybe my round about explanation wasn’t the best and maybe this feature wouldn’t save the world, but it would save several power button clicks over the course of the product’s life time. #FirstWorldProblems :~)
Primetime
Meridian completes the hat-trick in 2013 with the release of its Prime Headphone Amplifier. First the Explorer, followed by the Director, and now the Prime. The Prime is truly the centerpiece for a great audio system. It’s well suited for the home or the office, for headphones or powered loudspeakers, and for digital or analog input. The Prime is a quality audio component in both sight and sound. I enjoyed having it on my desk during the review process for both the way it looked and the way it sounded. Meridian’s attention to detail, low impedance headphone outputs, wisely designed asynchronous USB interface, separation of digital from analog circuitry, and stellar Analogue Spatial Processing (not to mention the forthcoming Prime Power Supply) all contribute to the Prime Headphone Amplifier’s excellent performance and its position on the Computer Audiophile Suggested Hardware List 
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Meridian Prime Headphone Amplifier and Prime Power Supply Image Gallery
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Product Information:
- Product - Meridian Prime Headphone Amplifier
- Price - $2,000
- Product Page - Link
- Where To Buy USA - Link
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* The Prime Power Supply will be available starting December 2013 for $1,250.
Associated Music:
Associated Equipment:
- Source: 15" MacBook Pro w/ Retina Display
- Playback Software: J River Media Center 19
- Network Attached Storage (NAS): Synology DS1812+
- Cables: Wire World Silver Starlight USB Cable
- Network: Cisco SG200-26 Switch, Baaske MI-1005 Ethernet Isolator, AudioQuest Diamond, Vodka, Cinnamon Ethernet Cables, Apple AirPort Extreme, PFSense Router / Firewall, Cisco DPC3000 Docsis 3.0 cable modem, Comcast Extreme 105 Mbps Internet Service
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