{"type":"firestarter.listing","listing":{"id":"lst_Gb_K3tZY","product_name":"TOPPING A90 Discrete Headphone Amp","category":"Headphone Amp","description":" \n\nOur best-selling amplifier \n\n“Mr. Clean.” “The Giant Killer.” “The Best Amp Ever.” These are a few of nicknames the TOPPING A90, our best-selling amplifier, has gained since its release. At its most basic level, it’s a balanced amp and pre-amp with tremendously clean and powerful output. At its broadest level, it’s become the benchmark by which all other solid state amplifiers below $1,000 are judged.\nD for Discrete\nThe A90 Discrete, or A90D, is an upgraded version of the groundbreaking A90. As its name suggests, the A90D uses fully discrete components in a complete redesign of the A90 NFCA module. Four discrete NFCA modules using 39 transistors each form the fully balanced amp architecture. The matched precision transistors ensure unparalleled distortion and noise performance. \nCalling all cans\nPlanar magnetic, dynamic drivers, IEMs—pick your poison, the A90D can handle it. Thanks to its high output voltage, high output current, and low output impedance, the A90D can push loads of power into high-impedance full-sized headphones or pare that power back in order to drive sensitive IEMs. And with an ultra-low noise rating and high dynamic range, the A90D does it all without producing any audible noise. \nSay goodbye to ground loop noise\nWhen multiple pieces of equipment are used in conjunction, ground loop noise can occur. Ground loop noise most often manifests as a buzzing or humming sound, which is capable of being loud enough to damage speakers. Although it's known to happen most often in single-ended feeds, it can happen in balanced feeds, too. \nThe A90D solves this issue with a GND/LIFT switch. When in normal use, set the switch to GND. If you encounter ground loop noise, set the switch to LIFT, which will change the ground point of the A90D from its chassis to the equipment it’s connected to, eliminating the noise. \nPre-amp mode\nWith the A90D in pre-amp mode, connect a power amplifier to drive bookshelf, desktop, or floor speakers. You can also connect the 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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_Gb_K3tZY' — this pins the purchase to this exact listing, skipping product search — plus request: 'Buy TOPPING A90 Discrete Headphone Amp' and a budget_max comfortably above $599.00 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."]}}