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Editors' Choice Award Winner 2013 - The Absolute Sound Magazine
"Best Solid-State Amplifier" 2008/2009 - The Absolute Sound Magazine
250-Watt THX Ultra II Amp Hits a 'Home Run'
Parasound's Halo A21 two-channel power amplifier has the brute force you need for ultra-realistic musical reproduction and hair-raising movie soundtracks. Its raw power is matched by elegant circuit design from audio guru John Curl in collaboration with CTC Builders.
"Highly Suitable for Driving Anything"
The Absolute Sound magazine rated the Halo A21 as the "Best Solid-State Amplifier" in the Winter 08 / Spring 09 issue, praising it as "highly suitable for driving anything from power-hungry planars like Maggies to low-sensitivity acoustic suspension cones."
The A21 is the two-channel version of Parasound's benchmark A51 five-channel amp, which the May 2003 issue of DVD Etc. magazine said hit the "proverbial home run." Matched JFET inputs, MOSFET drivers, and high-current bipolar outputs contribute to its exceptional performance.
"Close Enough to the Very Best"
The Absolute Sound magazine awarded the Halo A21 its "Editors' Choice" recommendation for 2012. "Though not the last word in solid-state amplification, the A21 comes close enough to the very best, at such an affordable price…"
"Its luxurious appearance is more than skin deep. Parasound’s A21 dispensed truly sumptuous sound," notes England's Hi-Fi News magazine for November 2011. "Demonstrating the control and grip of the Bryston and Anthem but with the velvety midband richness of the ATC, the Parasound’s ability to resolve detail, while remaining composed and easy on the ear, proved the equal of my ‘reference’ Levinson amplifier."
Balanced Inputs and Discrete Circuits
The A21 boasts balanced inputs with discrete circuits and XLR connectors. Beautifully implemented high-bias Class A / AB operation makes the most of an impressive 250-watt-per-channel power output at 8 ohms and 400-watts-per-channel at 4 ohms. The 1.2 kVA encapsulated toroidal power transformer with independent secondary windings for each channel and 100,000 µF power supply filter capacitance delivers an impressive current capacity of 60 amps per channel. The direct-coupled design uses no capacitors or inductors in signal path. The complementary MOSFET driver stage relies on the firepower of 16 beta-matched 15 amp, 60 MHz bipolar output transistors and works in combination with a JFET input stage.
'Instant Warm-up' Feature
Like all the other amps in the Halo product series, the A21 has Parasound's exclusive bias circuit, which permits the amplifier to sound perfect from the instant it's turned on, rather than having to wait for bias to gradually build up as the amp warms up over time. Very high bias allows greater Class operating range than others. Even Halo's implementation of its automatic turn-on feature is exceptional. Special relays bypass the AC "soft start" circuitry after it's done its job for the purest AC and the purest sound.
And That's Not All…
AC present, channel status, and high temperature indicators team up with DC Servo and relay protection circuits to keep this powerhouse running safely at peak performance for years of reliable service. Auto turn-on by 12-volt trigger or audio signal simplifies home theater and multi-room operation. Other features include heavy-duty 24k gold-plated five-way speaker terminals, gold-plated RCA input jacks, and a rear-panel ground lift switch.
Editors' Choice Award Winner 2013 - The Absolute Sound Magazine
"Though not the last word in solid-state amplification, the A21 comes close enough to the very best, at such an affordable price."
"Its luxurious appearance is more than skin deep. Parasound’s A21 dispensed truly sumptuous sound from Maxwell’s ‘Everwanting…’ with oodles of bass grunt and tight precision. The singer’s soulful multi-tracked vocal lines were depicted exquisitely within the track’s myriad percussion details. Demonstrating the control and grip of the Bryston and Anthem but with the velvety midband richness of the ATC, the Parasound’s ability to resolve detail, while remaining composed and easy on the ear, proved the equal of my ‘reference’ Levinson amplifier."
- Hi-Fi News magazine, November 2011
Audio Advisor - Parasound Halo A 21 Power Amp - Overview
Audio Advisor - Inside the Parasound Halo A 21 Power Amp
Audio Advisor - Parasound Halo A 21 Power Amp - Rear Panel
Audio Advisor Insight - Parasound High Value to Price Ratio
Audio Advisor Insight - Parasound in Hollywood
Audio Advisor Insight - Parasound Customer Service
Audio Advisor Insight - Parasound Amplifier Power
|Write Your Own Review|
This amp was such a massive improvement over the other amps I've owned it took my breath away. I've previously owned amps from B&K, Adcom, Rotel, Classe and Simaudio. When my Classe amp crapped out on me for a second time I decided to order the A21. Putting the Parasound in my system was like lifting a veil off my Vandersteen speakers. Everything opened up. Huge soundstage. Deep, effortless bass. Airy highs. Overall there is a rightness to the music that I didnt get before with my other amps. And this amp cost me less than two of my other amps. I can't recommend the A21 more hightly.
|- Joseph C, FL|
|A Definite Best Buy|
My Goldmund power amp lost a channel after 12 years of constant use. Goldmund wanted me to send the 100 lb amp back to Switzerland for repair. Instead, I bought an A21 to use until local repair shops could try to fix the Goldmund. That was two years ago. Local shops still can't fix the Goldmund. I'm in no hurry. The A21 is a very good stand-in in my high end system. Very good mids, natural highs and an extended bass. Built like a rock and runs cool. I can listen to a variety of music for hours without fatigue. BTW, the signal sensing auto-start is a nice feature for me since my Conrad Johnson preamp has no trigger provision. So how does it compare to my Goldman at many times the price? Low end is a bit looser. Not quite the timbre or dynamics of an amp costing about 4 times as much - but still pretty darn good! And at this price, it's an amazing accomplishment. I can go into the usual critique of voice, edge dynamics, strings, etc, but the true test remains enjoyment. I really enjoy locking myself in my stereo room for hours to just listen. I can't imagine any other amp at this price that can offer this power, construction and performance. This is definitely a Best Buy.
|- Ron L, AZ|
|Best amp I have owned yet.....|
I have had the following..... - legacy Adcom 2 channel amp - 2 Emotiva XPA-2 Gen 1's - 2 Emotiva XPA-2 Gen 2's - 1 Emotiva XPR-2 Monster and now this...... So far hooked up to Wharfedale Jade 7's and I think are better matched than my Opus 2-3's but have not tried those yet. Warm, more bass, and deeper sound. Still love my Emo's and will not sell them, at least not all of them yet.
|- Brett M, AZ|
|Killer Amp, Worth far more|
I purchased the Parasound A21 about two months ago,expecting nice performance for the price. What I got, after 50 hours of run in time, was far, far more than I expected.I love tube equipment, and the A21 reminds me of a quality tube amp with speed and dynamics of S.S. gear.It's driven by a Primaluna Dialogue Premium Preamp. Source components are a Marantz SA8005 SACD player, sometimes swapped for a Cambridge Audio CXC Transport and a Rotel RDD 1580 DAC. Speakers are Focal Aria 926's. The extremely accurate response across the audio spectrum along with very low to non-existent noise floor is incredible. The Amps ability to reproduce low level detail,sweet midrange,and extended highs clearly and in a natural,musical, non fatiguing way is fantastic.I have tried Amplifiers in my system costing up to three times the price of the A21, and none of them have sounded "Better". The best way I can describe it is that it sounds powerful, accurate, enjoyably musical at all levels. Parasound has put out a great Amplifier in the A21. To get the most satisfaction from it, I highly recommend it be used with other quality components-sources, speakers, etc. The build quality and cosmetics are top notch also. If you're looking for a great Amplifier at an almost bargain price considering all it is and does, buy one of these, you will be extremely happy!
|- Mike G, MN|
This nice, real nice. I can't speak to other amps in the same price range, but I can compare to what it replaced. I run a system with an Avid Diva II turntable, Ortofon 2M Black cartridge, Graham Slee Era Gold V phono stage, Marantz 8005 SACD player, and Focal Aria 936 speakers. All of this runs through an Emotiva XSP-1 preamp for switching and volume control. The amp being replaced is an Emotiva XPA-2. When I fired up the Halo A21 to listen to some of my favorite vinyl, there was a noticeable improvement. I don't have a lofty audiophile vocabulary, but I will say there is a change for the better in soundstage and overall richness tho the music. Steely Dan, Anita Baker, Kansas, etc all at different volume levels for my listening pleasure simply sounded better than I was accustomed to. I know that my review is subjective, but that is how you listen to and enjoy music. I'm now considering the JC 2 BP preamp to replace my Emotiva. The Halo A21 is something I can live with without feeling like I'm missing out on something better.
|- Larry R, MI|
|Part 2 of my Parasound Halo A21 Power Amplifier|
I said I would come back on my first review which was really just my first impressions of the amp. So I have now had several months with the A21 and I am still as impressed as I was back when I did my first review aka The Honeymoon Phase. You know... that phase you go through with a new piece of gear when it is so new and awesome you would have a hard time saying anything negative. The amp is everything I wanted and I have zero regrets. I just wanted to add- I dont do many reviews at all. Even though I didnt go into great detail, I think the man who did the first review on the A21 covered alot and clearly knows his stuff, I did come back for a second review and that is a first for me. Thank you Audioadvisor I will reccomend you and be back for any of my home audio needs in the future.
|- Linda R, FL|
|First impressions- Parasound Halo A21|
The amplifier arrived in a huge box made extra heavy duty with plastic straps and handles built into the sides. Inside that box was another box which housed the A21. Large pieces of styrofoam held the amp away from any contact with the exterior box. I wanted to describe the packaging to remove any concerns about your A21 arriving safely. Making the connections was pretty straight forward on the A21. I noticed Parasound included 2 wires for 9v to 12v DC triggering the amplifier on/off via your preamp/surround reciever. One was the smaller sub mini 2.5 mm wire which has the male 2.5mm connector on both ends. The A21 uses the 2.5mm for its trigger input. The other wire included has a male 2.5mm connector on one end and a slightly larger male connector on the other end which is what my setup required. I planned on using the auto on/off feature on the A21 which turns the amp on when an audio signal is present and turns the amp off within five minutes of no audio signal- unfortunately that didnt happen. The auto on/off has a nob to adjust the sensitivity but when the volume was not up fairly loud the A21 would shut off like it wasnt receiving a audio signal. This occured even with the sensitivity on maximum. The issue was solved by using the 12v trigger on/off with the extra connection wire Parasound included mentioned earlier. I prefer the quick on/off the 12v trigger provides over the auto on/off triggered by a audio signal or lack of one. *That was the only issue ,if you can even really consider it one, as far as set up. Performance- I was impressed with how quiet the A21 is even at high volumes. When the music pauses during changes in a song or when certain instruments are being played gently I hear no background noise at all. In between tracks it is completely silent. Not even the slightest hiss. This amp provides plenty of power, punch, and headroom for even the most demanding music/changes therefore improving sound quality as well. Even at lower volumes this amp sounds fantastic. At this point I have only had the A21 Halo hooked up for a couple days but already I am very impressed. Perhaps in 30-60 days I can give an updated review and go into more detail on the Parasound A21 Halo amplifier.
|- Linda R, FL|
|Obvious power, authority, control, speed, punch, slam, and refinement|
Hello, My wife and I listened to the Parasound A21 power amplifier along with the Parasound JC-2 preamplifier with the Usher Be-10s last weekend March 7th, 2009 with MIT speaker cables and interconnects. Sadly, the system only had a Rotel CD player for its source, so it was limited by that. However, this amplifier made it instantly clear that it has massive power to tap into at any moment and for long periods of time. It sounds as easy on the ears at very soft listening levels as it does when cranked up and then some. The abundant authority, control, punch, slam, speed, timing, pace, and drive were just downright visceral and intense. The bass tightness and impact were outstanding as well as offering terrific pitch definition and tracking of a bass line with the percussion without cluttering them together. The midbass was strong and tight too, yet musical and not overbearing one bit; just as the bass can be described. The midrange and treble were fluid, flowed like good red wine at an Italian dinner, and lavished our ears with sensuous saxophones, open and sonorous strings of plucked guitars, the epitome of intimate allure as the jazz singers wove their spells of song as if slinking around right in front of us with every breath and gasp for the next one rendered so realistically it was beguiling. The presence of the component was an asset to this system and listening experience as it allowed, and made, the speakers come to life with a palpable bloom and airiness that let our song by John Denver warm our hearts like never before due to how lifelike it sounded. This amplifier offers depth of soundstage and solidity to the foundation of bass that is exemplary and easily equal to other components many times its modest cost. We were thoroughly impressed and would gladly invest in one, or two, of these without any doubt at all. Richard Schram of Parasound told me in an Email from last summer that the A21 will offer about 15 to 20 wpc in full, legitimate class A mode when bridged mono. The class A high biasing comes through in stereo mode, as we listened to it, for about 7.5 wpc, and makes this amplifier very smooth and easy to listen to with no harshness or listener fatigue at all. It is extremely neutral and does not muffle, veil, dull, or slow down the sound at all. It breathes performance into your system so that you can enjoy your favorite music so easily. This system, with this Parasound A21 in it, is one of the most emotionally engaging systems that I, and now we, have ever heard; be it solid state, tube, or both, and regardless of cost or brands included. That says a lot for those who really know about and have heard what is out there to audition. I have auditioned 130 brands and sold 78 brands in addition to those, so I have a pretty good idea of this stuff, along with doing it since I was 16 and am now age 40, so theres two dozen years of experience to hopefully lend credibility to this personal review. The amplifier is also very visually appealing in general appearance, fit and finish first rate, and my WAF Wife Acceptance Factor is 100% positive. There are no perceivable flaws or shortcomings of any kind. You would have to, and I do mean have to, invest much more money to get noticeably better sound. We are planning on getting two of them and running them in a vertically bi-amplified manner at first or bridging them and having fun with that sheer power. Keep in mind that Mr. John Curl, formerly of Mark Levinson, is the designer of this product. That in itself says a great deal about the technical competency that this amplifier was conceived with. Bravo for a job very well done !! Sincerely, Tom & Erin near Allentown, PA.
|- Tom F, PA|