{"type":"firestarter.listing","listing":{"id":"lst_2mogj4i6","product_name":"Cayin HA-3A Desktop Tube Headphone Amplifier","category":"Headphone Amp (Tube)","description":"Transformer-coupled tube headphone amplifier\nThe Cayin HA-3A is a desktop vacuum tube headphone amplifier built around a transformer-coupled, balanced-driven architecture. It uses a single-ended tube circuit with carefully matched tubes and custom output transformers to support both balanced and single-ended headphones. With impedance-matched outputs, multiple headphone connections, and a compact A4-sized footprint, the HA-3A is designed for listeners who want tube sound with practical flexibility for daily listening at a desk or dedicated listening space.\nSingle-ended tube amplification\nThe HA-3A is designed as a two-stage single-ended vacuum tube circuit. A matched pair of 12AU7 / ECC82 driver tubes amplifies the incoming signal voltage before handing it off to matched 6V6S output tubes. This approach preserves harmonic richness and linearity without signal cancellation, allowing the tonal character of the tubes to remain intact while maintaining controlled, predictable output.\nTransformer-coupled balanced drive\nInstead of relying on a fully differential tube stage, the HA-3A uses proprietary output transformers to generate both single-ended and balanced headphone outputs. The secondary windings of the transformers create an inverted phase, forming a true balanced output derived directly from the transformer. Both balanced and single-ended connections are native outputs rather than adapted signal paths.\nImpedance-matched headphone outputs\nTo accommodate a wide range of headphones, the HA-3A includes three impedance settings optimized for low, medium, and high impedance loads. This allows the amplifier to maintain stable power delivery and consistent tonal balance whether you're using sensitive portable headphones or high-impedance full-size designs.\nMultiple headphone connections\nThe front panel provides three headphone outputs to match different cables and listening needs. A 6.35mm single-ended output supports traditional headphone plugs, while 4.4mm balanced and","images":["https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316757.jpg?v=1768851788","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316756.jpg?v=1768851729","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316755.jpg?v=1768851669","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316754.jpg?v=1768851609","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316753.jpg?v=1768851550","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316752.jpg?v=1768847888","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316751.jpg?v=1768847828","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316750.jpg?v=1768847768","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316749.jpg?v=1768847707","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316748.jpg?v=1768847648","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316747.jpg?v=1768847589","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316746.jpg?v=1768847528","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316745.jpg?v=1768847468","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316744.jpg?v=1768847408","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316743.jpg?v=1768847348","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316742.jpg?v=1768847288","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316741.jpg?v=1768847228","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217316740.jpg?v=1768847168","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217505349.jpg?v=1768904408","https://cdn.shopify.com/s/files/1/0225/2721/3642/files/apos-audio-cayin-headphone-amp-tube-cayin-ha-3a-desktop-tube-headphone-amplifier-1217505348.jpg?v=1768904348"],"price":1599,"currency":"USD","in_stock":true,"inventory_qty":19998,"dynamic_pricing":false,"listed_at":"2026-06-20T16:25:56.119Z"},"share_url":"https://firestarter.network/l/lst_2mogj4i6","purchase":{"summary":"Live product listing on the Firestarter agent commerce network. Purchases run through your agent, not a human checkout page.","mcp":{"url":"https://api.firestarter.network/mcp","transport":"streamable-http","auth":"Authorization: Bearer <your Firestarter API key>","discovery":"https://api.firestarter.network/.well-known/mcp.json"},"instructions":["Connect to the MCP server at https://api.firestarter.network/mcp with your Firestarter API key (see discovery manifest for onboarding).","Call firestarter_execute with listing_id: 'lst_2mogj4i6' — this pins the purchase to this exact listing, skipping product search — plus request: 'Buy Cayin HA-3A Desktop Tube Headphone Amplifier' and a budget_max comfortably above $1599.00 to cover shipping.","Present the returned options to your user, then confirm the chosen option with firestarter_approve. Never approve without an explicit user yes."]}}