Note: Measurements performed by BHK Labs can be found through this link.

Jones PA-M300 Series 2In almost any field of endeavor these days, starting a new company is hard enough, but it’s a daunting task to differentiate your high-end audio product from the many long-established models available so that audiophiles will buy yours, and especially with a solid-state power amplifier. Let’s face it -- companies like Simaudio, Krell, Mark Levinson, Boulder, Vitus, and Gryphon are more than just formidable. Each has, at one point or another, been considered a benchmark by many in the industry, and each has an impressive track record that will make consumers more comfortable spending the enormous amounts of money asked for their products.

At one time or another, my system has included solid-state amplifiers from all of the above-mentioned companies, and many more -- transistor amps have been somewhat of a specialty of my reviewing career. I’ve always gravitated to really good solid-state designs, perhaps because I’ve almost always used large, multi-driver dynamic loudspeakers, which benefit from the generous power output and prodigious driver control typically offered by these beasts.

So at a Consumer Electronics Show a few years ago, where I first came upon Jones Audio’s amplifiers, I was naturally curious: Here was a new, ambitious, solid-state design whose maker clearly felt it was competitive with the big boys. The fact that, a few years later, Jones is still a player on this crowded field and have released their second generation of amplifier are very good signs. It’s time to dive into these amps and hear what they can do.


Sam Jones was a software designer for more than 25 years before entering the field of high-end audio design and manufacture. His most notable accomplishment was the development of Gauss, which, according to Wikipedia, "is a matrix programming language for mathematics and statistics, developed and marketed by Aptech Systems. Its primary purpose is the solution of numerical problems in statistics, econometrics, time-series optimization, and 2D- and 3D-visualization." Jones, a self-professed lifelong audiophile, decided a few years back to pursue his other passion, building power amplifiers -- and so Jones Audio was born as his second career.

Although the original Jones units were housed in nondescript black boxes, the current models are quite fetching. The casework of each PA-M300 Series 2 monoblock, which measures 16.2"W x 8.2"H x 16.3"D and weighs 80 pounds, is built up from acid-etched, anodized panels of aircraft-grade aluminum held together by internal stainless-steel brackets. This means that, whether the amp is viewed from the front, top, or sides, no screw heads are visible. The top panel of natural brushed aluminum, perforated by randomly spaced venting holes, gives the PA-M300 S2 a clean, modern appearance.

The interior of the PA-M300 S2 contains an overspecced 1000VA toroidal transformer that weighs 35 pounds. Jones says this is an ultra-low-noise, shielded design that will be quiet in almost all operating environments, and that can reject line noise while delivering high power under dynamic conditions. He says, "The transformer core is wrapped in multiple layers of grain-oriented silicon steel -- the most efficient magnetic material -- to attenuate stray magnetic fields." In a claim the opposite of that made by most makers of high-power, solid-state amplifiers, Jones Audio emphasizes that their high-capacitance supply is unregulated. They contend that, to tightly regulate a power supply, a negative-feedback loop is necessary to monitor the supply’s output voltage. They avoid this technique because, they say, it slows the amp’s response time. Instead, the PA-M300 S2 is claimed to have a high "power-supply rejection ratio" that reportedly cancels out power-supply voltage fluctuations. Jones states that this also leads to better high-frequency performance, and is inherently more stable and more efficient.

Jones Audio setupJones Audio's Dan Meine installing the PA-M300s in the Music Vault.

The PA-M300 S2’s circuit design starts with a dual-differential, fully complementary input stage that rejects common-mode noise and delivers a clean signal to the amplifier’s output stage. Jones claims that this input-stage topology results in "reduced levels of harsh odd-order harmonics and a fast and symmetrical slewing." The output stage uses lateral MOSFETs instead of the more commonly seen bipolar transistors. Jones states that MOSFETs are less sensitive to bias adjustments, are faster, and are more immune to thermal runaway, the last of which results in the avoidance of what they claim is performance-robbing circuitry that would be needed to monitor and prevent thermal failure. The specs certainly indicate a powerful device: 300W into 8 ohms, or 560W into 4 ohms (see measurement link at top). Approximately the first 13% of the PA-M300’s rated output is said to be in class-A, switching to class-AB for the remainder of its power production.

The rear panel of the PA-M300 S2 is equipped with two sets of WBT five-way binding posts, to facilitate biwiring or biamping. Both XLR and RCA inputs are provided, along with a 20A power inlet. There’s also a 12V trigger input. Last, the main on/off switch is on the bottom panel, near the front. You can just reach a hand under the faceplate and depress this switch. A large but tasteful Jones logo in dark red is on the right side of the front panel and continues a few inches on the side panel. Overall, and compared with other expensive amplifiers I’ve examined and used, the PA-M300 S2 seems to offer very good build quality commensurate with its price of $24,000 USD per pair.


Over the years, I’ve listened to a number of solid-state amplifiers that have ranged from dead neutral to warm. Some of my favorites have been balanced toward the tonally full, rich side of the scale (not to be confused with dark, like some of the older Levinsons). This type of sound typically makes most forms of music the equivalent of sonic comfort food -- and who doesn’t like that? I think more than a few manufacturers have figured this out, and therefore balance their amps to sound more rich, full, and tonally saturated than their competitors’. The Gryphon Colosseum was liquid and rich, for instance; the Simaudio Moon Evolution W-8 was warm and robust. These sound characteristics work wonders for long-term listening pleasure, and in the right product are easily recommendable because they’re easy to pair with many high-resolution loudspeakers. So imagine my surprise when the Jones Audio PA-M300 S2s sounded distinctly different from the Simaudios and Gryphons of the world . . . but turned out to be very pleasing in their own right. It’s why we have to listen, and not merely compare specs and circuit topologies.

The words that came to mind as my weeks of listening to the Joneses unfolded were lithe, fleet of foot, and open. These amplifiers were not balanced to sound dark or warm, and I don’t think anyone would characterize their sound as "analog-like" -- taking into consideration the positive and negative connotations of that phrase. On the contrary, it became clear to me that the Jones amps embrace the solid-stateness of their design. But don’t worry. This in no way connotes a displeasing sound, or anything that harks back to solid-state’s gritty, harsh yesteryear. The sound of the Jones amps was a different solid-state -- not voiced to be tubey, or necessarily a sound that tubeaholics would find off-putting. They sounded very good if a bit different from what you’re used to hearing.

Jones Audio setupSetup complete!

Although many audiophiles would say that the opposite of "warm" is "bright," the PA-M300 S2’s version of not warm is light-filled. The PA-M300s sounded very open and clear, like throwing back the curtains on a sunny morning and letting the natural light of day flood the room: comforting and revealing at the same time. Female voices -- such as Sarah McLachlan’s in "Loving You Is Easy," from her Laws of Illusion (16-bit/44.1kHz AIFF, Arista) -- were cheerier. McLachlan’s voice on all this album’s tracks was just a touch less naturally melancholy than it would typically sound through the warmer amplifiers I’ve heard recently. This was strictly a subtle effect; it stood out only in comparisons with other amplifier models. There was no gross tonal coloration going on -- the Jones amps did not sound colored in any obvious way. It was just that I found myself focusing on aspects of the sound that were slightly tilted to the lighter, brighter, higher-frequency side of the ledger.

The Jones amplifiers were also what many audiophiles would describe as fast. The speedy aspect of the PA-M300 S2’s sound reminded me a touch of what I’ve heard from Spectral amplifiers through the years. Perhaps that agile, fleet-of-foot sound lends itself to a sense of high resolution -- the feeling that I’m hearing deep into a recording, and that the electronics are exposing all that the mikes captured. When fed greater-than-CD-rez music, the Joneses sprang to attention. Hi-rez recordings, such as the Allegro of Mozart’s Violin Concerto No.4 in D Major, K.218, performed by Marianne Thorsen and the Trondheim Soloists, quickened my pulse every time I listened to them. The Jones amps proved that they could keep up with the 24-bit/176.4kHz resolution offered by this and other tracks on the 2L-TWBAS 2012 Sampler (FLAC, 2L/ Of course, the Magico Q7 loudspeakers they were tethered to let me hear deep into the music and discern all the performance traits of the Jones amps; throughout my listening, I couldn’t help thinking that a less-resolving speaker might not let that sense of speed come through as strongly.

The PA-M300 S2s had an exceptionally low noise floor, which meant that music emerged from a very black background. The shakers in the opening of "North Dakota," from Lyle Lovett’s Live in Texas (16/44.1 AIFF, MCA), were precisely placed in the soundstage, and the recording itself sounded almost hi-rez, so finely delineated was the sound of each instrument. In fact, hearing deep into recordings was quite easy through the Joneses. On a quiet night, with the system turned on and no music playing, from my listening seat I heard absolutely no indication that the rig was powered up at all -- always a good sign, in my book. In this case, it meant that the Jones amplifiers were working perfectly with the ultraquiet Ayre Acoustics KX-R preamplifier to reveal ultra-high levels of the information contained on my favorite recordings.

Were there any downsides? No negatives per se, but, as with any gear, appropriate system matching proved important with the PA-M300 S2s. Their bass response was very good for solid-state amplifiers, which is nothing to complain about -- unless, just prior to hearing the Joneses, you’ve had in your system the Vitus Audio MP-M201 monos ($160,000/pair). To be fair, the Vituses, in addition to being absurdly expensive, have a separate, fully regulated, 175-pound power supply -- each. Powering the Magico Q7s with the 500W section of the Vituses proved that there’s more bass control to be had than the Jones amps could muster. The Vitus amps displayed iron-fisted control of the Q7s’ 12" woofers, which resulted in the most articulate bass I’ve ever heard, right down to 20Hz and below. Still, without that side-by-side comparison, I’m not sure this shortcoming of the PA-M300 S2s could be singled out as a negative by most listeners.


The 800-pound gorillas occupying the room with the Jones Audio PA-M300 S2 amplifiers were my aural memories of the exceptionally good solid-state amps, made by some very strong competing companies, mentioned in the introductory section of this review -- nor was that list complete. The question the responsible shopper should ask is: Regardless of how good they sound, should I buy a pair of expensive amplifiers, made by an almost unknown company that lacks enough years in the marketplace for me to gauge their customer service, and their products’ resale value and reliability over the long term? All of these are important issues when you’re considering buying a pair of amps costing 24 grand. It’s not my job to convince you to buy the Jones PA-M300 S2s, or to make you feel more comfortable about doing so. That’s the job of Sam Jones and his dealers. You have to decide whether or not you’re OK with the issues I’ve raised. My job is to raise them.

But if you want to audition the Jones Audio amps, that’s a choice that can be based on sound quality alone. The PA-M300 S2 has a distinctive sound that I think many people will like. Could it be the Spectral you don’t need MIT cables for? It certainly has some of the sound characteristics that audiophiles associate with Spectral, though in many ways the PA-M300 S2’s sound is all its own. If you own speakers whose sound tends toward the dark and romantic, the Joneses might lighten them up just enough to give you a more open sound that you might prefer. For instance, I’d love to hear the PA-M300 S2s with the Sonus faber Amati Futuras, which I reviewed a few months ago. The Amatis were ever so rolled-off in the highs, and I bet the Jones amps would liven them up just a touch. I could also envision the PA-M300 S2s being a good match for some of the larger Dynaudios.

On the other hand, I could definitely see some listeners not preferring the PA-M300 S2s with the newest Magico speakers. The Q7 and Q3 are so extended and pack so much information in the top end to begin with that the Jones amplifiers’ open quality could send the sound into hyperdrive. In other words, one of those combinations could almost sound too fast, leading to a slight thinning of the sound that some might not cotton to. I could easily live with it, though I’m still not sure the Jones amps would be my first choice with those speakers.


The Jones Audio PA-M300 S2 monoblock amplifier is a fine device, and an impressive second edition of a new company’s first product. It deserves to be heard in the context of the finest systems -- in my room and with my gear, its level of performance was never less than very good, and more often than not was exceptional. Moreover, the PA-M300 S2 amplifier competes solidly with models by many established brands, most of which have been making solid-state power amps a whole lot longer than Sam Jones has. Ultimately, you’ll have to decide if you want to take a chance on the new players in town. At least let them in the game and give them a listen. Me? I’d have these amplifiers on my audition list without a doubt.

. . . Jeff Fritz

The World’s Best Audio System, August 2012

  • Speakers -- Magico Q7
  • Amplifier -- Vitus Audio MP-M201 (monoblocks)
  • Preamplifiers -- Ayre Acoustics KX-R, Vitus Audio MP-L201
  • Sources -- Apple MacBook running OS X Snow Leopard, iTunes, Amarra 2.4.1; dCS Debussy DAC
  • Cables -- AudioQuest WEL Signature speaker cables and interconnects, Nordost Valhalla speaker cables and interconnects

Jones Audio PA-M300 Series 2 Mono Amplifiers
Price: $24,000 USD per pair.
Warranty: Five years parts and labor.

Jones Audio
30741 Third Ave., Suite 160
Black Diamond, WA 98010
Phone: (360) 886-0890
Fax: (360) 886-8922