Parasound A31 Three Channel Power Amplifier

Published On: March 25, 2013
Last Updated on: October 31, 2020
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Parasound A31 Three Channel Power Amplifier

Parasound has a longstanding history when it comes to amplifiers. One of the newer entrants to that legacy is the Parasound A31 three channel power amplifier. Andrew Robinson evaluates the A31 to see if it carries on the Parasound name.

Parasound A31 Three Channel Power Amplifier

By Author: Andrew Robinson

Andrew Robinson began his career as an art director in entertainment advertising in 2003, after graduating from Art Center College of Design. In 2006, he became a creative director at Crew Creative Advertising, and oversaw the agency's Television Division, where he worked for clients such as TNT, TBS, History, FX, and Bravo to name a few. He now has one of the most popular AV-related channels on YouTube.

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Since its founding in 1981, Parasound has become one of the industry's most venerable brands, offering scores of products that historically have garnered high praise amongst discerning enthusiasts, though the wares have always been offered at reasonable prices. Halo, Parasound's, well, halo or flagship line of products was introduced in the late Nineties, though it continues the company's commitment to excellence to this day. The newest product, the A31 three-channel amplifier reviewed here, is a first for Parasound. Parasound has never offered a three-channel amplifier and, while three-channel amps are nothing new within the industry, fans of the company are probably asking themselves (and Parasound) what took so long.

Additional Resources
• Read more multi-channel amp reviews from HomeTheaterReview.com's writers.
• Explore more reviews in our AV Preamp and Stereo Preamp review sections..
• Find a pair of Bookshelf Speakers or Floorstanding Speakers to drive with the A31.

Three-channel amplifiers were all the rage a few years ago, but then sort of faded away. They didn't go extinct, but they fell out of favor as the "it" solution. I suppose as money became tight, people went back to all-in-one solutions, i.e., five- and seven-channel amplifiers or AV receivers. The purpose of a three-channel amp is to bring multi-channel capability to an existing two-channel system. What I mean by this is that a manufacturer of a three-channel amplifier, in this case Parasound, assumes that the customer has an existing stereo amp (or two mono amplifiers) that he or she likes and simply wishes to add amplifier channels for a center channel and surround speakers. For a Parasound customer, this could mean that he or she is already in possession of either a pair of JC1 monaural amplifiers or an A21 stereo amp. I don't mention the A23 stereo amplifier, because it offers up less power compared to the JC1, A21 or the A31. Another benefit of having a three-channel amp over, say, a five- or seven-channel one is that it gives you the ability to selectively power up only certain components when need be, thus saving you money at the meter. For example, let's say your home theater and two-channel system are one and the same and you use a A21 Halo amp for your left and right mains and an A31 for your center and rear channels. If you only wish to listen to music, then you needn't power up the A31 at all. Make sense? Those of you with seven-channel systems can still benefit from a three-channel amplifier, as it gives you the ability to run your front three speakers, while utilizing a pair of stereo amps for your surround and rear channels, which could be lesser amps in terms of power than what is required for your front three channels. So that is how a three-channel amplifier comes into play. The question that remains is whether the A31 is any good.

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The A31 retails for $3,000, which puts it square in the mid-fi budget category, for it's not quite Emotiva/Outlaw affordable, but a far cry from Mark Levinson/Krell/Classe/McIntosh/ARC/Pass prices. From the outside, the A31 looks every bit a Parasound Halo product, clad in its trademark brushed silver facade, though Halo products are now being offered in black, too. The A31 utilizes the same chassis as its fellow multi-channel and stereo siblings (including the JC1), measuring 17.25 inches wide by nearly eight inches tall (with feet) and just over 19 inches deep. It's hefty, too, weighing a respectable but not unmanageable 65 pounds. The front panel features Parasound's logo on top with three small indicator lights below the THX logo and a small backlit power button resting in the far left corner. The sides of the A31 are adorned with heat sink fins that feature rounded edges, so as not to cause any physical harm to the customer or installer charged with moving the A31 into its final position. Around back, you'll find a host of input/output options, as well as a few features not commonly found on most amplifiers, budget or otherwise. Moving from left to right the first thing you'll notice are the A31's massive metal rack handles. Just inside the left handle are the A31's "Turn On Options," which include an auto/manual power switch and a 12-volt trigger. The manual switch allows you to set the A31's auto power up feature to either auto (which has a sensitivity dial), manual (using the front-mounted power button) or via a 12-volt trigger. There is even a loop out option for daisy-chaining several amps together if you so desire. Each of the channel inputs are neatly arranged, well spaced and labeled 1, 2 and 3, respectively. Each features XLR as well as RCA input options that are selectable via a small toggle switch. To the left of the input options rests a gain knob that gives you control, plus or minus 6dB off normal or THX reference, to help level match the A31 to other amplifiers - presumably ones that fall outside of the Halo lineup of products. This is a decidedly pro feature, one I'll discuss in a moment. Below the input options rest a pair of five-way binding posts, one pair for each channel. Along the far right side of the back panel rests a large master on/off switch as well as a standard AC power receptacle.

Behind the scenes, the A31 is quite a brute, churning out a healthy 250 watts per channel into eight ohms and 400 watts per into four. The A31 is THX Ultra2-certified as well. The A31's internal circuitry was designed by none other than John Curl, a longtime Parasound collaborator and designer extraordinaire, with more than a few hits to his name. The A31, like all Halo-branded amplifiers, is a high-bias Class A/AB amplifier, meaning the first few watts - in this case seven - are delivered in pure Class A fashion before switching over to AB status. The signal path is direct-coupled, meaning no capacitors or inductors are used anywhere in the signal path, and is capable of full power output down to 5Hz. The A31 employs matched pairs of JFETs for its input/pre-driver stages and matched pairs of MOSFETS in its driver stage. It also utilizes eight beta-matched, 15-amp 60Hz output transistors for each channel. The A31 plays host to a large encapsulated toroid transformer (1.5 kVA) with separate, independent windings for each of its three channels. For more details on the A31's inner workings, as well as design notes, please visit the A31's product page on Parasound's website.

Like all Parasound products, the A31 comes with a full five-year parts and labor warranty in the United States and in Canada.

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The Hookup
I received the A31 amplifier from Parasound shortly after attending the Rocky Mountain Audio Fest. It arrived, along with a matching A21 two-channel amp, to serve as a personal reference in not only my review systems, but also in my in-home mastering suite. I had been a Parasound customer previously, having owned both the Halo and Classic line of products, so I was not unfamiliar with the brand or its sound.

Installing the A31 into my Sanus equipment rack was fairly straightforward, thanks to a) the A31 being of rack-mountable size and b) Parasound including rack ears with purchase to facilitate such an installation. That last part is a big deal (for me at least), as I've encountered no other brand that does this free of charge. Instead, other brands always offer rack ears as an optional extra, sometimes a costly one. I installed the A31 along the bottom of my rack with the A21 resting above, though there are three or four rack spaces between the two in order to allow for proper ventilation.

Once installed, making the requisite connections was a breeze. I connected the A31 to my Integra DHC 80.2 AV preamp, using individual runs of balanced interconnects courtesy of Monoprice. From there, I connected the A31 to a host of different loudspeakers, ranging from my trusty Tekton Design Pendragons to a complement of Jade 1 bookshelf speakers from Wharfedale. I even went so far as to use the A31 in conjunction with professional commercial cinema loudspeakers from JBL. Regardless of the speaker choice, all were connected via 12-gauge bulk speaker cable from Binary, a SnapAV company.

It should be noted that I ran the A31 both as a main amplifier and as a secondary one, meaning I used it to power my mains exclusively, as well as rear channels. When more than three channels were needed, it was always paired with my Parasound Halo A21. I found the two to be interchangeable in terms of sonics, i.e., I couldn't tell them apart.

The rest of my system was as follows: Dune-HD Max and Oppo BDP-103 as the primary source components, Behringer Feedback Destroyer feeding into a single JL Audio Fathom f110 subwoofer with parametric EQ filters from Room EQ Wizard, and a SIM2 Nero single-chip DLP projecting onto a 120-inch Acoustic4K screen from Elite Screens. I'm not big on "break-in," but I do believe amplifiers, especially those with Class A and AB topologies, do need a little bit of time to warm up, so I gave the A31 a good 30 minutes or so of just playing music at background levels before sitting down for any critical listening sessions.

Read about the performance of the Parasound A31 amplifier on Page 2.

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Performance
I began my critical evaluation of the A31 amplifier with some two-channel music by way of Moby's "Everloving" off the hit album Play (V2). Right away, the A31 proved exceedingly resolute in that it shone appropriate light upon every detail and nuance in a wholly convincing and natural way. The control it exhibited over my speakers' drivers was impressive, but not so much so as to call attention to itself. Instead, the amp and drivers seemed to work in harmony. I was taken aback by the level of low mid-bass articulation that was present, which I found equal to that of its high-frequency performance. The whole sonic spectrum was (largely) uncolored and sounded wholly natural to me, possessing zero grain, edge or other maladies that would've otherwise spoiled the performance.

The A31's high-frequency performance was one of openness, but also one that remained natural in its timbre. Cymbals sounded like real cymbals, versus artificial enhancements in order to show off traits such as air and decay. Not to say that these weren't present via the A31, it's just that neither drew attention to itself in a "look at me" fashion. Likewise, the bass was incredibly resolute and impactful, and though I have heard a bit more heft from my Pendragons, I preferred the A31's articulation and speed, for I have a subwoofer for brute force. Dynamics, much like the rest of the A31's performance, felt right, in that they were neither trumped up nor sluggish. As for the A31's soundstage, I found it to be fairly three-dimensional, provided the material called for it, meaning it was capable of extending beyond the front baffles of the speakers and further back as well, while the side to side extension was wall to wall and beyond. As with everything else I've just described about the A31's sound, its soundstage definition was equally detailed and neatly arranged, but in a wholly natural-sounding way.

Next I cued up another favorite, Mike Oldfield's Tubular Bells III, and the track "Far Above the Clouds"(Warner Bros. UK). This track is a little more chaotic in comparison to "Everloving," but even with its more bombastic dynamic swings and high-frequency energy, the A31 never faltered. In truth, I never felt as if I was even tapping its full potential, as the resulting sound was effortless. The explosion of bells was precisely that - an explosion - and while they may have rocked my room, they never overpowered my ears nor caused fatiguing. Instead, the bells were clearly delineated from one another and presented with such focus and control that their presence in my room was one of three-dimensionality, as they were not only arranged side to side but front to back very clearly. Again, the dynamic swings of this track were incredible and at times more than a little palpable, in that they quite literally stirred the soul. Bass and low mid-bass control was again exceptional, as was definition and presence amidst the high-frequency onslaught happening around it. Moreover, the A31 wasn't critical (at all) of my choice of speaker, as it managed to reproduce similar results with all the options I had on hand, whether they were lower-sensitivity bookshelf speakers (Wharfedale) or commercial cinema loudspeakers (JBL).

Moving on, I went with an old pop favorite, The Wallflowers' hit "One Headlight" off their album Bringing Down the Horse (Interscope Records). Front-man Jacob Dylan's vocals were presented in their full unaltered dry but sultry state. I noticed a bit more inflection in Dylan's voice than through previous amplifiers, as well as a bit more surrounding air, which lent a greater sense of dimension, not to mention scale, to the performance and to his physical being. Other features that jumped out at me were the track's many snare hits and rim shots, which were rendered with just a bit more detail and nuance throughout, compared to what had been provided by previous amplifiers employed in my system. Low-level detail was brilliantly fleshed out and, even when I dropped the volume to background levels, the experience didn't diminish, it merely scaled.

Moving on to movies, I cued up a guilty pleasure of mine, the disaster flick 2012 (Columbia), on Blu-ray disc. This time, with the A31 having to play nice with its two-channel sibling the A21, I couldn't detect any dissimilarities between the two when using one for mains and the other for center and/or rear channel duty. Dialogue was always intelligible, arguably more so as a result of the A31's power and resolution as described above. There were moments when previously garbled lines of dialogue came through just a touch clearer, resulting in my being able to clearly hear what was being said, even if that hadn't been the sound mixer's intention. Actors always came across as natural-sounding, with their scale appropriate to a) the action on screen and b) to my judicious use of my Integra's volume knob. When the world does literally begin to crumble beneath the characters' feet, the resulting sound was truly epic and, yet again, I felt as if I was able to discern more of it due to the A31's (and A21's) incredible clarity and definition throughout. As with my first tests, I have heard a bit more low-end oomph, but again, I tend to cross my speakers over at anywhere between 50 and 60Hz (80Hz for bookshelf speakers), so that uber-low bass is going to be dealt with by a sub and is only being pointed out here for evaluation purposes. Dynamics ran the gamut from wow to I think I may have messed myself, depending upon the scene and my choice of overall volume. Regardless, the A31 never wavered nor seemed to run out of juice. The entire performance was one of terrific balance and sheer effortlessness.

I ended my evaluation of the A31 with another Blu-ray disc, Iron Man 2 (Paramount). I chaptered ahead to the Monaco race scenes, set my volume to a level appropriate for a movie of this magnitude and was simply transported. The cracks of Ivan Vanko's whips were positively violent in their dynamic snaps and the resulting electrical crack was so vividly rendered that it made me shudder. More importantly, even with each crack spiking at around 100dB, the resulting sound was never fatiguing, sharp or brittle. I suppose I've heard a touch more top-end sizzle, but I'm not certain I'd say the A31 is wrong in its portrayal, as everything simply felt right in its delivery. Vocals again were intelligible and natural in their timbre, not to mention true to their respective actors, but also carried with them a wonderful sense of weight and physical presence. Explosions and crashing cars rocked my room, yet were pushed through effortlessly and with terrific focus and control - no warbled drivers here. What I actually found most impressive was how balanced the background score seemed to be in the face of all that was unfolding in front of it. I'm not suggesting that other amps simply ignore the score but, as with the rest of the performance, there just seemed to be a little more presence to it, lending a grander, more epic touch to the whole sequence. Not that it needed help.

Earlier in the review, I spoke about the A31's gain controls and how that was more a pro feature aimed at pairing different amplifiers together. Well, I used it (sparingly) when employing professional cinema equipment elsewhere in my signal chain, as it allowed me to better integrate the pro gear with the rest of my consumer-sourced equipment. While this isn't going to be of much use to 99 percent of those who buy an amp such as the A31, I found it very useful and, as a result, a huge selling point.

The Downside
The A31 is a phenomenal overachiever as far as amplifiers go. However, there are a few items worth noting before making your final purchasing decision. First, the A31 is large and in charge, meaning its physical requirements may be a deal-breaker for some and/or in certain installations. Also, because it is but a three-channel amp, it will require you to have additional amplifiers present in order to power a full five- or seven-channel setup, which also requires more space. It's possible to get a Halo-branded amp with five channels. However, this may not allow for the same level of flexibility should you wish to power your stereo mains differently than the rest of your speakers. To each his own, I guess.

Along with being on the large side, the A31 does run warm and, under spirited listening, it can even get hot so proper ventilation is an absolute must, with open air installations being the best option, though by no means mandatory.

Lastly, I found the A31's binding posts to be a bit pedestrian and, well, not up to the same standard as the rest of the amplifier's build and sonic quality. While they were completely functional, they just felt cheap in comparison to everything else the Halo affords you.

Competition and Comparisons
Among its three-channel peers, I found the A31 to compete very favorably against both the Mark Levinson No 533H and the Krell Evolution 3250e. The Levinson No 533H has a slightly more sultry sound in comparison to the A31, but one that is still pleasing, though it costs decidedly more at $10,000 retail. On the other hand, the Krell Evolution 3250e has a slightly more spirited sound versus that of the A31, in that the Krell is a bit more dynamic and taut throughout. Like the Levinson, the 3250e also retails for far more than the A31, coming in at $10,000 as well. In all fairness the 3250e, even at $10,000, is a far cry from what Krell charges for another three-channel amp of theirs, the Evolution 403e, which retails for $25,000. I'm not suggesting the A31 bests the Evolution 403e, I'm just using it to help qualify (or perhaps quantify) its high-end value. All three amplifiers are unique and special in their own rights and deciding which is right for you is going to boil down to personal preference, as well as budget.

For more on these amplifiers and others like them, please visit Home Theater Review's Multi-Channel Amplifier page.

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Conclusion
I'm not going to lie and say that $3,000 for a three-channel amp is wholly affordable, but I'd hardly put the A31 in the category of aspirational either, as that category is well populated. I hate the term mid-fi, as that carries with it a sort of negative connotation that the customer is somehow settling for middle of the road, which the A31 is clearly not. For me, the A31 from Parasound's Halo line of products is aspirational but obtainable, in that it competes very favorably with far costlier competition, yet can be had by many with just a little foresight and financial planning. The best part of a product like the A31, or any found within Parasound's lineup, is that the reliability is on par with a wood-burning stove. I've gotten word of users with ten-plus-year-old Parasound amps still performing as well as the day they were taken out of the box and, while this reliability may cost Parasound some sales down the road, it does go a long way toward justifying the A31's slightly higher price point.

In all fairness, I didn't request the A31 for review so much as I sought it out in order to utilize it in my reference system and mixing studio. It just so happened to not suck and live up to every expectation I had prior to its arrival. Is there a market for it? I think so, though undoubtedly traditional stereo and five- or seven-channel amplifiers will always be more popular than three-channel ones. That said, the Parasound Halo A31 three-channel amp is among the best I've encountered thus far in my travels and one that I'm not going to be parting with any time soon. If you're an existing Halo customer or simply want to take your two-channel rig to new multi-channel heights, you'll be hard pressed to do better than the A31 sonically, though you can definitely spend more.

Additional Resources
Read more multi-channel amp reviews from HomeTheaterReview.com's writers.
Explore more reviews in our AV Preamp and Stereo Preamp review sections..
Find a pair of Bookshelf Speakers or Floorstanding Speakers to drive with the A31.

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