The A21SE added power and control to the A21a formula while keeping pure class-A operation.
Class-A unit: the chassis runs hot by design and needs free airflow. The supply capacitors are the usual failure point after 20+ years; Sugden still services the A21 line in the UK.
Marks that can be entered for this maker: Model / catalogue number, British capacitor code (Hunts, Mullard), Japanese capacitor code (Nichicon, Chemi-Con, ELNA), EIA component code, Version & era marker.
Nothing predates 2004; components only push the date later.
Sold-listing reading: fair EUR 2,000, good EUR 2,300, excellent EUR 3,899 EUR · 11 sold listings · as of 2026-10-17. Asking prices only - these are live listings, not completed sales. 11 listing(s) in EUR observed on 2026-10-17 via the HiFi Shark marketplace aggregator; min/median/max of the observed asks are used as fair/good/excellent, which is a reading of the ask spread, not a condition grading. Listings in other currencies were seen and counted for the spread but are not converted here (see the journal): GBP x2, PLN x1.
Evidence: Sugden — official ampography · HiFi Shark — live listings aggregator