very powerful watts

handling not easy

Heard Parasound hooked up to Wilsons at AXPONA and was sold. This amp has the muscle to control your speakers. Have the P5 pre and the sound is sweet. Soundstage is great, my Magico S3's disappear. This is a giant killer and only egos of having a brand name will keep you from experiencing this at these prices. I have had these on Focal Sopra 2, 3's, and Be II's Bookshelfs also so that is 3 great speakers companies and they all loved this amp.

None I can find in a year of usage. Only problem is if and when bridged, it can only be used for 8 ohm speakers.

I bought my A21 in 2008 to replace an Adcom 555II to drive my Infinity renaissance 90. The A21 out of the box controlled the Rens top to bottom bringing out tight bass and crystalline highs that I never heard before with the Adcom. The amp in silver is nice to look at and 65lbs it is a beast that competes with krell and Levinson at a quarter of the cost. I have had this amp for 11 years and never had an issue of any kind.

Speaker terminals on back are made of cheap plastic and the amp is built in Taiwan but designed by John Curl and put to market by an American company but as far as sound and build quality this amp ca not be beat at this price point. Discontinued replaced by A21+ costing 3200.00

After many years of dreaming about purchasing the A21, I have it now, and it is a truly remarkable amplifier. Plenty of grunt, quality build, great highs and mighty lows. I now also have a A31 plus two A23s.

Nothing really, other than it not being a low power amp, i don't know specifics, but id assume its not the most energy efficient unit, likes to run warm. But it's worth it!

I am not an audiophile and I have no clue what pro audiophiles are talking about whenever I read their saying. And I am too short of adjectives and adverbs to write a review as audiophile does. I have a degree of science but I have had hard time to understand the scientific narratives of audiophiles. But I can say this Halo A 21 is remarkable and am very pleased with. It was a long and winding road to get to the Halo though. I wasn't happy with the sound of Magnepan and Adcom 5500 always. So I was going to buy Adcom GFA 580 SE with preamp but the recent review of Adcom wasn't that positive. Then I ordered Emotiva XPA 2 believing it is good deal for the money. But I canceled the order when they told me it is made to order and would deliver after two weeks while the web site says it is to be shipped in 48 hours. No integrity of doing business. Then I decided to take a chance of Parasound after the president of company replied within 12 hours of my inquiry.

I only listen to classical music and my ultimate desire is the replication of the natural sound with electronic equipment. As long as it sounds as if no electronic machine is engaged, I'll be happy with it. I couldn't tell which component of what I have was at fault. So I ordered Cambridge CXN to eliminate analogue connection and separate DAC altogether.

The final outcome was very impressive and surprising. The distortion of high frequency is significantly down and the sound of low frequency is alive. I hear the detail of all the percussion. Especially the piano playing was as real as being natural. I couldn't tell any difference from the Mag 3.7 with McIntosh which the dealer demonstrated a few days ago.

Money well spent. I am very happy with it. There is some clipping but it is tolerable. For $2,500 it was worth and enjoyable. It was more than I expected.

After my 15 year old Goldmund amp broke, I bought an A21 in 2015 to fill the need until either the Goldman could be repaired or replaced with a top of the line power amp. After almost 2 years, local shops are still trying to fix the Goldmund and the A21 has done a wonderful job in my system. Strong bass, natural mids and extended highs. In addition to the trigger voltage feature, it has a input signal sensor that I use to couple it with my Conrad Johnson preamp because the CJ does not have a trigger outlet.

Very good sound - maybe a bit lacking in timbre and soundstage when compared to some of my expensive amps of the past. Built like a tank. Runs cool, even when pushed to high volumes. I'm in no hurry to replace it.

Just want to say thank you very much to "J. Curl" and "Parasound" for create this A21 Monster ..... Damn Good Job Guys.....satisfied from Jakarta Indonesia .... Salut

My journey to refresh my audio system began with the replacement of my Sonus Faber Grand Piano Domus with the Sonus Faber Cremona Auditor M. After that, it was the DAC (Perpetual Technologies P1/P3 combo) to Wyred4Sound DAC2 DSDse, then my CD Transport (Northstar 192 Transport to Wyred4Sound MS-2 music server), and finally my Power Amp (I ran the DAC direct to the Power Amp). This took the longest as I wanted to make sure that the eventual replacement to my Bel Canto S300 would be a worthy one. Besides equipment, I also changed out my cables (DH Labs HDMI cable from Wyred4Sound MS-2 to DAC, SoundSilver Clarity silver conductor XLR cables from DAC to Amp, & TelluriumQ Ultra Black loudspeaker cables from Amp to Loudspeakers). Hence, it was a total refresh.

I did my usual research online, and trawled the various online audio magazines for suitable candidates. My requirement for the replacement amp includes relatively high power (more than 300W at 4 ohm), good damping factor, high current capable, reliable, and of course musical and within my budget (not more than $3000). Since my Bel Canto is a Class D amp, I am ok with looking at another Class D amp to replace it, although I did not restrict my search to just Class D amps. That was a good move, because that was when I came across the Parasound A21.

I am acquainted with Parasound, as my first audiophile quality CD player was a Parasound CDP-1000, and later I bought a Parasound DAC-1500 to upgrade the overall source quality. That was back in 1996. Back to the present time. Over the course of the next 3 months, I went on and auditioned similar priced amps from Wyred4Sound, Bel Canto and eventually the Parasound. I guess it was the fact that the A21 is a Class A/AB design that made the difference (between the Wyred4Sound & Bel Canto). The Class D amps, while very good sounding and good at what they can do for the price, there is a noticeable hardness in the upper registers and frequencies. This became very apparent once I noticed it, and it is present in all recordings and playback. For the A21, no matter how hard it was driven, there was no hardness at all. The upper registers and frequencies sounded sweet and very listenable. In crescendos and complexes musical passages, the amp sounded relaxed and musical. It did not give me any listening fatigue at all. In fact, it made listening to music enjoyable again.

As mentioned in any other reviews, the A21 does not favor any particular frequency range. He music just came through as it was meant to be. Of course,the quality of the sound is dependent on the quality of the recorded music, as well as the source and ancillary equipment. In my system, the A21 really allowed me to enjoy my music in ways I did not before. The entire system is more coherent and musical than before the refresh. And now Inhabe the added benefit of convenience with the Music Server from Wyred4Sound. Listening to music has never been this fun and easy. I did not miss the cleaning and preparing of my CDs before playing etc. After all, listening to music is supposed to be fun and relaxing.

In summary, the A21 was the final piece of my equipment refresh journey. It was an apt one, as it truly allowed wonderful music to be played in my new system. For the price, it is an excellent value and, most of all, it does not leave me wanting to look for something better (which I am sure there are for a lot more money). As so many reviewers have said before me, the A21 is a no-brainier and indeed highly recommended! Thank you Parasound for making such a wonderful product at this price point, and bringing musical enjoyment to the masses! I am once again a fan.

I have had amplifiers by McCormack, Pioneer, SAE, Odyssey and a few others. This amp by Parasound is head and shoulders better than those amps.

I had wanted an Odyssey Stratos for many years. But as fate had it, when I got one tI had nothing but problems with intermittent noise and hum. After many, many months of trying to get it fixed I got rid of it. When I took the plunge with the A21, it was massive and quite powerful. But it delivered in a subtle way, as well. It was good with at low volumes and natural sounding at higher volumes. I paired it with a Parasound P3 preamp and it was just.... astonishing.

The only other amp I heard and liked as much, was a Musical Fidelity integrated dual mono that was twice the price.

I noticed an earlier review comparing the A21 to an Emotiva amp, and since I owned and reviewed an Emotiva XPA-3 amp back in 2010, I thought I'd review this excellent amp.

I bought the Halo in 2012, after moving out of a small townhouse and into a largish detached home. I had been using the XPA-3 with Paradigm Signature S6 speakers, a emotiva cd player and their XDA-1 DAC as a pre amp. I'd always watched the volume levels in the townhouse since the side walls are shared with neighbors, so when we got to the house, I was finally able to crank it up, and I mean loud.

That's when I noticed for the first time that the sound seemed bright, and uncomfortably so. At the moderate levels I'd been using previously and the previous pre amp, an Anthem TLP-1, it wasn't forward sounding, but with the XDA it sure was. Many different solutions were tried, but to make a long story short, after researching Parasound I thought the A21 would be an improvement.

Was it ever. I compared it side by side with the XPA amp. Using certain tracks, I could get distortion or sibilance when vocalists pronounced an "esss" at volume peaks of 82db. Swap in the A21, same tracks and volume, absolutely no distortion. It was bizzare and repeatable. That's when I noticed that the A21 had nicer highs, and mid range vocals were smooth and detailed like the XPA wasn't. Better bass too, more accurate. I sold the XPA amp. It is a decent entry level amp, and an improvement over receivers, but in the end that's about it.

The A21 is built like a tank, and images like I'd never experienced. It has many options including variable gain knobs, auto turn on/trigger on, rca outputs, XLR/RCA inputs, and Class A operation for the first 10 watts. Class A is nicer sounding although it is subtle for most. By comparison, the only thing the XPA amp line has is the XLR inputs.

After some more experimenting, I got their P7. Then I got Audioquest Type 4 speaker cable(in bulk by the foot at $120 for 24 feet.), and Morrow Audio MA3 interconnect cables. Every change brought about an improvement in the end result. The amp has the benefit of having great detail and resolution so better speakers will reward you with air and detail that gives superior imaging than a bargain brand amp. After 2 years, I really feel like it's the last amp I"ll ever buy.