Parasound has announced more-powerful "plus" versions of its best-selling A 21 and A 23 power amplifiers that were in continuous production since 2003. The new Parasound Halo A 21+ and A 23+ employ higher-capacity power supplies to increase output from 250 to 300 watts and 125 to 160 watts, respectively.
Parasound and John Curl, their primary design consultant for the past 30 years, targeted power supply transformers and filter capacitors as the foundation for power output increases. They also further refined audio quality in the signal-path and related circuitry with upgraded gold-on-gold internal connections to improve resolution and increase transparency. In fact, the design team consensus is that the sonic improvements are as impressive as the power increases.
With its larger 1.3kVA power transformer and 108,000 uF power supply capacitance, the Parasound Halo A 21+ output has jumped from 250 to 300 watts into 8 ohm loads, 400 to 500 watts into 4 ohms, and from 750 to 1000 watts in bridged mode. Further improvements have increased the signal-to-noise ratio from 112 dB to 115 dB, increased crosstalk from 63 dB to 70 dB, while the THD (total harmonic distortion) at full rated power output has decreased from 0.2% to 0.1%. Not surprisingly, these improvements pushed its net weight over 18% from 60 to 71 pounds.
Like the original A 21, the new A 21+ amplifier gives users a choice of balanced and unbalanced inputs with loop outputs, and variable gain controls. The most visible rear-panel difference on the A 21+ is new CHK Infinium heavy duty speaker terminals originally developed for the top-of-the-line 2 x 400w Halo JC 5.
The new Parasound Halo A 23+ is similarly improved, with a larger 1.1kVA power transformer and 54,400 uF power supply capacitance. This supports increasing power output from 125 to 160 watts into 8-ohm loads, 225 to 240 watts into 4 ohms, and from 400 to 500 watts in mono bridged mode. The A 23+ has balanced and unbalanced inputs with adjustable gain controls, loop outputs, and new higher-performance speaker terminals adapted from the popular Parasound HINT 6 integrated amplifier.
Both new amplifier models feature more-refined Halo styling, including solid aluminum end caps with gold highlights. Both models include 12-volt DC triggers with loop outputs, plus more sensitive audio auto turn-on.
The Parasound Halo A 21+ and A 23+ are now available in silver or black finishes through the company's Canadian distributor Gemsen for $4,500 and $2,100, respectively.