Parasound A21 Amplifiers

4.9/5 (10 Reviews) MSRP : $1995.00


Product Description

Halo A21 Two-Channel Amplifier
  • Continuous power output (20 Hz - 20 kHz): 250 watts RMS x 2 at 8 ohms, 400 watts RMS x 2 at 4 ohms, 750 watts RMS x 1 (bridged mono mode) at 8 ohms
  • Current capacity: 60 amperes peak per channel
  • Power bandwidth: 5 Hz - 100 kHz, +0/-3 dB at 1 watt
  • Total harmonic distortion: < 0.2 % at full power
  • IM distortion: < 0.04 %
  • Slew rate: >130 V / µsecond
  • Dynamic headroom: > 1.5 dB
  • Interchannel crosstalk: > 80 dB at 1 kHz; > 63 dB at 20 kHz
  • Input sensitivity: 1 V for 28.28 V, THX Reference Level
  • Input impedance: 33 k ohm unbalanced; 66 k ohm balanced
  • S/N ratio: > 112 dB, input shorted, IHF A-weighted
  • Damping factor: > 1100 at 20 Hz
  • Voltage: 110V – 120V
  • Dimensions: 17.25" wide, 7.625" high (7" without feet), 19.12" deep
  • Net weight: 60 lbs.
  • Manufacturer''s limited warranty: 10 years parts, 5 years labor


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    Reviews 1 - 5 (10 Reviews Total) | Next 15

    User Reviews

    Overall Rating:4
    Value Rating:5
    Submitted by MagnusVer a Audio Enthusiast

    Date Reviewed: June 11, 2011

    Bottom Line:   
    The A21 has got to be one of the best kept secrets ever. I bought it second hand for less than half the original retail price. Wonderful performance driving any speaker load, and I've run it with seven different speakers thus far, both conventional and planar.

    The amp is like a diesel engine, pulling an incredible amount of low-end grunt from recordings where I had formerly never known it existed. It has been a tremendous pleasure going through my old dust covered disc collection discovering some real hidden gems I'm glad I hadn't discarded.

    It is definitely a beast of an amp physically, and proper space is needed if that is a concern in your application. You'd better allow for about 22" of depth if you use XLR's.

    I had a McIntosh MC7200 at the same time as the A21, and after over a year of comparison I sold the Mac. The A21 just trumped it in every way. Though I did like the blue VU meters on the Mac...

    One small negative is the XLR sockets do not have a locking feature. Other than that this is one of the best amps available for the money bar none. Buying one second hand is a classic no-brainer. This one is a keeper.

    Expand full review >>

    Used product for:   More than 1 year

    Duration Product Used:   Audio Enthusiast

    Product model year:   2008



    Overall Rating:5
    Value Rating:4
    Submitted by cocopeep a AudioPhile

    Date Reviewed: June 9, 2007

    Bottom Line:   
    The parasound Halo A21 is a heavy amplifier. Great quality looks and build, handles on the back and heat fins on the side, the blue lights look good at night. 250 watts per channel, it has plenty of power to run inefficient speakers, such as my JSE infininite slope 1.8 with 4 drivers. Using Cardas quadlink speaker and interconnect, this needs a good break in period and open cabinet where the heat can escape. After many hours of playback, the soundstage opened up with instruments heard in great detail. With 1.2 kVA encapsulated toroid power transformer with independent secondary windings for each channel , and 100,000 µF power supply filter capacitance , this amp delivers superb bass, this amp will never break a sweat! This one amp will outperform my 2 B&K ST202 put together in a bi-amped setup.

    Expand full review >>

    Used product for:   Less than 1 month

    Duration Product Used:   AudioPhile

    Product model year:   2004

    Price Paid:    $1600.00

    Purchased At:   longplayer stereo Go



    Overall Rating:5
    Value Rating:4
    Submitted by Lee V a AudioPhile

    Date Reviewed: June 9, 2007

    Bottom Line:   
    The Parasound A21 is an extremely heavy amp weighing in at 60 pounds. It is rated for 250 watts per channel, 8 ohms. It is capable of running in mono mode, with balanced or unbalanced connections, and gain adjustments on the back. Great build quality, large handles on the rear (may be needed when moving this) and is deep at 22 inches, requiring a large and strong shelf.
    Upon using the Parasound Halo A21 during the break-in period, I noticed the soundstage grow wide and deeper. This amp needs a good amount of time to break in, and produces a good amount of heat, since it runs class A for the first 10-15 watts or so. 1.2 kVA encapsulated toroid power transformer with independent secondary windings for each channel, 100,000 µF power supply filter capacitance allows for this amp to deliver sudden bass impact when needed without any strain whatsoever. This workhorse will compete with the best amps such as Pass or others costing thousands more.

    Expand full review >>

    Used product for:   Less than 1 month

    Duration Product Used:   AudioPhile

    Product model year:   2004

    Price Paid:    $1600.00

    Purchased At:   longplayer stereo Go



    Overall Rating:5
    Value Rating:5
    Submitted by tlqualman a Audio Enthusiast

    Date Reviewed: December 19, 2006

    Bottom Line:   
    I had upgraded my speakers (PBN Audio Montana SPX) after listening to them in the shop powered by a set of Halo JC1 mono blocks. I got them home and hooked them up to my McIntosh 6 ch home theater amp ( 85/watts/ch ) which is not a bad amp but they were missnig something. I can not afford nor have the room for the mono blocks so my salesman suggested I try using the Halo A21. I brought the amp home hooked it up and there was the sound that I so loved in the showroom. I finally had a set of speakers that could produce everything on a recording and an amp that allowed my speakers to perform there best. The A21 had absolute control, no matter what volume I play the system at I never hear it become harsh or strained. I feel I am getting about 95% of the performance of the JC1 for a lot less cash. I don't think I have ever got this much bang for my audio buck before. On top of the A21's great performance I think it is a beautiful piece of equipment just sitting there in the rack with it's blue glow. This amps beauty is more then skin deep.

    Expand full review >>

    Used product for:   More than 1 year

    Duration Product Used:   Audio Enthusiast

    Product model year:   2006

    Purchased At:   The Sound Station



    Overall Rating:5
    Value Rating:5
    Submitted by Joseph Gallo a Audio Enthusiast

    Date Reviewed: December 12, 2006

    Bottom Line:   
    This is one serious amp.I cant believe Parasound can market this product for 2 large.I shopped at high end shops in the north Jersey area and they showed me amps at two times the price that could not shine the shoes of this beast.I recieved the amp via ups and they left it on my stoop while I was at work.No need to worry cause no ordinary thief was gonna be able to carry this piece of audio excellence away.Boxed up the weight was 77 lbs. I almost died draging it down the stairs to my listening room. The a-21 comes in a double box and at that weight it was a good thing.Putting it on the bottom of my equipment rack was a monumental chore,first this amp is 19' deep I had to slide the rack out 6" just to fit it in and the weght 60 lbs unboxed made me break out in a sweat.Once hooked up and turned on all was well worth it . This amp sounded broke in right out fo the box.It controlled my Infinity Renaissance 90"s with relative ease .The soundstage was huge,the bass deep tight and fast.the 90"s are not an easy speaker to drive and if you get the right amp the sound is exhillirating.I ve finally got the right amp,and i didnt have to take a second mortgage on my house. O.K. so the amp is made in Taiwan if you can get by that you have a great looking amp Designed by John Curl and put to market by a reputable american company with a 10year warranty what more can I say if you buy a mega buck amp its your lose I think Ill go buy some music with my savings.

    Expand full review >>

    Used product for:   1 to 3 months

    Duration Product Used:   Audio Enthusiast

    Product model year:   2006

    Price Paid:    $1700.00

    Purchased At:   Sound City NY




    Reviews 1 - 5 (10 Reviews Total) | Next 15

    Review Options:  Sorted by Latest Review | Sort by Best Rating


    The Sugden A21-a

    My local dealer has a Sugden A21-a integrated for sale... Now this amp is rated at 25w 'pure class A' and it sounds fantastic with the speakers he has at the showroom (Tannoy's and Kef) but i dont know whether this will match the Paradigm studio 20? I have read a lot of reviews on this amp, but no o ... Read More »

    150 watt JM Chorus speaker powered by 250 W Halo A21

    Hi guys, Im thinking about buying a new pair of JM Labs 726 V speakers I listened to at my local dealer. These speakers are rated to handle about 200-250 watts. My Parasound Halo A21 amp puts out 250 watts @ 8 ohms and I am running those into a pair of JSE Infinite slope 1.8 that can handle 300 wa ... Read More »

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    Hello anyone interested in reading... I am curious to hear some thoughts about the following situation. Right now I am powering my PSB Platinum T6's with a Parasound Halo A23, which has been a great combination, but I am also quite aware that my speakers are in need of a bit more power to really ... Read More »

    Halo A21

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    how about Sugden A21 and PMC TB-2S

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