The Parasound Halo A 21+ power amplifier features high-quality and proven class A/AB technology, resulting in a durable and superior audio component that has been built to meet strict quality and performance standards. Experience exceptional audio and long-lasting reliability with the A 21+. Key Features: 300 watts x 2 @ 8 Ω RMS, both channels driven Circuitry designed by legendary John Curl High bias Class A/AB operation 60 amperes peak current per channel Stable with speaker impedance dips to 1.5 Ω Balanced inputs with discrete circuits CHK Infinium, custom 5-way speaker binding posts, Gold Plated RCA inputs Direct-coupled signal path, no capacitors or inductors Changes from the original A 21→A 21+: 250 → 300 Watts (8Ω) 400 → 500 Watts (4Ω) 750 → 1000 Watts (bridged) Filter cap: 88,000 uF → 108,000 uF S/N: 112dB → 115 dB THD (at full power): 0.2% → 0.1% Crosstalk (20kHz): 63dB → 70dB Transformer size: 1.2 kVA → 1.3 kVA Weight: 60 LB → 71 LB Refined Halo cosmetic with aluminum end caps & gold highlights Updated rear panel with heavy duty speaker terminals from JC 5 Upgraded internal gold on gold audio connections Updated auto turn on circuit