Summary: 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.
Summary: 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.
Summary: 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.
Summary: 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.
Summary: 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.
Summary: Good Lord is this a great, great amplifier. The sonic prowess and downright agility this amp can muster with a dregree effortlessness is worthy of accolades. You have a world class designer coupled to a company that's large enough to take advantage of economies of scale and deliver those savings to the consumer. Thank You John Curl, Thank You Parasound! Finally, I've got the sound I've been after but could never justify the cost.
Summary: I have to completely agree with the other reviewers. The A21 provides world class sound at a mid-fi price. This was on my shortlist of amps 200 watts+. I got the upgrade bug and went for a Pass Labs X250.5. The Pass is a work of art and is a real brute. Throws the largest and widest soundstage of any amp I have owned and had tremendous bass slam but like most high end solid state, it is extremely hyper detailed in the upper frequencies. Now I'm not slamming Pass Labs.
Summary: I can second all that has been written before me (two reviews), even though they sound to me like they were written by the PR dept. of Parasound. I have had two Threshold Amps, most recently the S500. Both were wonderful. I have been updating my system and thought to audition the A21 just for fun. I was blown away! I sit at the front of the Chicago Symphony Orchestra, so I'm used to live sound. . isn't that the goal.
Summary: So many accolades have been heaped upon this amp that I risk merely repeating what has gone before ... but in a world where audiophile sound equipment pricing has reached astronomical and outrageous levels, praise must be given to outstanding products that sell at (comparatively) modest prices. The Parasound A21 is just such a remarkable product!
Summary: Most people write reviews to later read their own posts, and I am no exception. In this case, I feel compelled to write about the Halo A 21 because of its incredible value and mind-boggling sonic excellence. That a $2000 amplifier could sound this good defies logic. I first became interested in the HALO line because of their extremely well received JC - 1 mono amps.