Amp/Preamp Asylum: REVIEW: Parasound A-23 Amplifier (SS) by twest820

Model:	A-23
Category:	Amplifier (SS)
Suggested Retail Price:	$850
Description:
Manufacturer URL:	Parasound
Model Picture:	View

Review by twest820 ( A ) on March 05, 2006 at 11:30:08
IP Address: 71.112.23.130

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This amp hauls. I was auditioning various power amps as possible upgrades from my NAD C352 and within 30 seconds of spinning up the first CD with the A23 plugged in I'd decided to buy the A23. Admittedly, it helped I'd saved the A23 for last, but there really wasn't any contest between the NAD, Arcam, and other power amps I was comparing the A23 to. The A23 is a fast, precise amp that's exactly where it should be when it should be there. The result is a sense you're listening to music being played rather than being reproduced. Most of the other amps I've listened to which are priced within a factor of two of the A23 seem to struggle with bass. The A23 doesn't have blurry bass (NAD), weak bass (Arcam), or lagging bass (Denon), among other problems. Timing is consistently quick and responsive across the spectrum and the sound is richly detailed and precise. I auditioned the A23 side by side with a Halo JC-1 monoblock pair using bi-wired Dali Helicon 800 speakers and a Halo P3 preamplifier and, quite frankly, couldn't hear any difference between the A23 and JC-1s. Considering the JC-1s cost seven times as much as the A23, this is a strong mark in the A23s' favor.
In short, the A23 delivers excellent sound for any amp, and at a mid-fi price too. Quit looking and buy one. I wholeheartedly agree with dog-or-man's concluding paragraph; with the exception of price the A23 has the qualities of a reference amp and I really can't imagine what I'd upgrade to---the only amps I can find with lower THD are US > $15k Krells. After I switched my stereo to an A23 based vertical bi-amp even my completely un-audiophile friends started commenting on how nice the sound was.
See my Parasound Halo P3 preamplifier review for comments on how the A23s work in a vertical bi-amp with the P3 and differences between the RCA and XLR inputs. My only substantive complaint about the amp is the gain control knobs are tall and marked only with a small dent. This makes precise adjustment difficult since it's hard to accurately judge the knob's positioning; I've taken to using a pair of dial calipers and measuring the offset across the knob to keep channel gains matched across all four channels in my vertical bi-amp. Not ideal, but it works well enough and isn't much fuss. Parasound has the usual rear panel silk screening and there's plenty of space around the knobs so there's no reason why Parasound couldn't screen a series of radial lines around the gain control knob and use a low profile knob with an easy to gauge marking on it.
An interesting design oddity is XLR pin 2 on the amp's inputs is shorted to RCA signal while pin 3 seems to tie to a virtual ground. The A23's innards are almost entirely discretes and most of the traces run on the underside of the board, making it hard to probe around to reverse engineer the amp's schematic, but presumably Parasound does this so they can deliver balanced and unbalanced signals to a balanced input stage and save a bit of cost. If this is what Parasound's doing it's a nice bit of design, though it has the minor drawback of making the balanced input sensitivity half of the unbalanced sensitivity. You have to turn up the volume on the preamp by 3dB to compensate. Another oddity is the amp has RCA out as well as RCA in. It's not clear to me what purpose having RCA out, other than you can use it to jumper the amp's channels together in a vertical bi-amp which uses RCA interconnects. This is kind of handy, but it would probably be more useful if Parasound put the parts budget towards a (carefully changeable!) switch which would let you provide a common balanced or unbalanced input to both channels without the requirement of an additional cable.

Product Weakness: Dimming and brightening of power switch and Parasound LEDs doesn't clearly signal on or off in daylight; a better way of telling if the amp is on is to look at the channel active LEDs. But these can be difficult to see in direct sunlight.
Product Strengths: Delivers a feeling of live music. Significantly outperforms everything else I've listened to in its price range and goes toe to toe with the US $2.5k to $6k amps I've listened to. Balanced inputs and an unusually low THD. Has gain controls (even if they are cumbersome to use) and the +12V DC power on trigger works well with the P3. Good building block component for bi-amping. Readily available used. Oh yeah, it looks cool too.

Associated Equipment for this Review:
Amplifier:	Parasound Halo A23 passive vertical bi-amp
Preamplifier (or None if Integrated):	Parasound Halo P3
Sources (CDP/Turntable):	Cambridge Azur 640C v1
Speakers:	Dali Suite 2.8
Cables/Interconnects:	doubled Goertz MI2 (equivalent to Goertz MI3), Kimber 8VS XLR 2/2/4 bi-wired interconnects between P3 and A23s, Kimber 4VS RCA-XLR 2/2/4 bi-wire interconnect between 640C and P3
Music Used (Genre/Selections):	classical to metal
Room Size (LxWxH):	18 x 12 x 9
Room Comments/Treatments:	Semi-walled off, carpeted living part of great room. Dimensions in feet.
Time Period/Length of Audition:	about six months
Type of Audition/Review:	Product Owner