{"product_id":"fosi-audio-gr40-tube-dac-headphone-amplifier-preamplifier","title":"Fosi Audio GR40 Tube DAC, Headphone Amplifier \u0026 Preamplifier","description":"\u003ch3\u003eFosi Audio GR40 Tube DAC, Headphone Amplifier \u0026amp; Preamplifier\u003c\/h3\u003e  \u003cp\u003eBring the character of vacuum tube audio and modern digital connectivity to your listening space with the Fosi Audio GR40 Tube DAC, Headphone Amplifier \u0026amp; Preamplifier. Combining an ESS ES9028Q2M digital-to-analog converter, two replaceable 5654W vacuum tubes, and a dedicated headphone amplifier, the GR40 offers a versatile solution for high-resolution music playback and personal listening. With Bluetooth 5.1, USB-C, optical, and coaxial digital inputs, along with stereo RCA and 3.5mm headphone outputs, the GR40 brings modern convenience and classic Hi-Fi styling together in one compact desktop component.\u003c\/p\u003e  \u003cp\u003eAt the heart of the Fosi Audio GR40 is the ESS ES9028Q2M DAC, designed to deliver detailed and accurate digital-to-analog conversion for your favorite music. Through its USB connection, the GR40 supports PCM audio up to 32-bit\/384kHz and DSD256, providing compatibility with high-resolution music files and playback software. Optical and coaxial digital inputs offer additional connectivity for compatible CD transports, televisions, and other digital audio sources. The GR40's tube preamplifier stage uses two 5654W vacuum tubes to introduce the rich harmonic character associated with traditional tube audio, creating an engaging listening experience that combines modern digital precision with vintage-inspired sound.\u003c\/p\u003e  \u003cp\u003eWireless music playback is equally convenient with Bluetooth 5.1 connectivity, powered by a Qualcomm QCC3031 Bluetooth chip. Supporting SBC, AAC, aptX, aptX HD, and aptX Low Latency codecs, the GR40 allows you to stream music wirelessly from compatible smartphones, tablets, and computers. aptX HD provides enhanced Bluetooth audio quality when paired with compatible devices, while aptX Low Latency helps reduce audio delay when watching movies or videos. An included external Bluetooth antenna supports a reliable wireless connection, while front-panel input indicators make it easy to identify and switch between Bluetooth, USB, optical, and coaxial sources.\u003c\/p\u003e  \u003cp\u003eFor dedicated headphone listening, the Fosi Audio GR40 includes a 3.5mm stereo headphone output designed for compatible headphones with impedances ranging from 32 to 300 ohms. The integrated headphone amplifier delivers up to 250mW into 32 ohms and 40mW into 300 ohms, offering flexible performance for a range of wired headphones. A headphone-priority system automatically mutes the rear RCA output whenever headphones are connected, making it easy to transition between private listening and speaker playback without manually switching outputs.\u003c\/p\u003e  \u003cp\u003eBeyond its headphone capabilities, the GR40 functions as a stereo tube preamplifier with a dedicated pair of RCA analog outputs. Connect the GR40 to compatible powered speakers, an integrated amplifier, or a dedicated power amplifier to bring its DAC and vacuum tube preamplification into a larger stereo system. Independent bass and treble controls provide additional sound customization, allowing you to adjust tonal balance to suit different recordings, connected equipment, and personal preferences. A multifunction volume knob also serves as the power and input-selection control, providing convenient operation without a complicated interface.\u003c\/p\u003e  \u003cp\u003eDesigned for both performance and visual appeal, the GR40 features a compact metal enclosure, two exposed vacuum tubes, and decorative tube rings that bring classic Hi-Fi character to modern desktop audio systems. The tubes can be replaced with compatible alternatives, giving enthusiasts the opportunity to experiment with different tube characteristics. An external 12V power adapter supplies the GR40, while its USB-C connection is dedicated to digital audio data rather than power delivery. Whether you're exploring high-resolution music files, streaming wirelessly from your phone, or building a dedicated headphone listening setup, the Fosi Audio GR40 delivers an appealing combination of digital audio performance, tube preamplification, and everyday versatility.\u003c\/p\u003e  \u003ch4\u003eSpecifications\u003c\/h4\u003e \u003cul\u003e \u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Fosi Audio\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eModel:\u003c\/strong\u003e GR40\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Tube DAC, stereo preamplifier, and headphone amplifier\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eAudio Channels:\u003c\/strong\u003e 2-channel stereo\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eAmplifier Design:\u003c\/strong\u003e Hybrid digital audio conversion and vacuum tube preamplification\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eDAC Chip:\u003c\/strong\u003e ESS ES9028Q2M\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBluetooth Chip:\u003c\/strong\u003e Qualcomm QCC3031\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eVacuum Tubes:\u003c\/strong\u003e 2 × 5654W\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eTube Configuration:\u003c\/strong\u003e Replaceable vacuum tubes\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eCompatible Replacement Tube Types:\u003c\/strong\u003e EF95, 6AK5, 6AK5W, 403A\/403B, 6J1, 6J1P, and other electrically compatible alternatives\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBuilt-In DAC:\u003c\/strong\u003e Yes\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBuilt-In Headphone Amplifier:\u003c\/strong\u003e Yes\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBuilt-In Stereo Preamplifier:\u003c\/strong\u003e Yes\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eTotal Audio Input Types:\u003c\/strong\u003e 4\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eUSB Audio Input:\u003c\/strong\u003e 1 × USB-C\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eOptical Digital Input:\u003c\/strong\u003e 1 × TOSLINK\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eCoaxial Digital Input:\u003c\/strong\u003e 1 × coaxial S\/PDIF\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eWireless Audio Input:\u003c\/strong\u003e Bluetooth 5.1\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eSelectable Input Modes:\u003c\/strong\u003e Bluetooth, USB, optical, and coaxial\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eMaximum USB PCM Resolution:\u003c\/strong\u003e 32-bit\/384kHz\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eMaximum USB DSD Resolution:\u003c\/strong\u003e DSD256\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eUSB Function:\u003c\/strong\u003e Digital audio data connection only; does not power the GR40\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBluetooth Version:\u003c\/strong\u003e 5.1\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBluetooth Audio Codecs:\u003c\/strong\u003e SBC, AAC, aptX, aptX HD, and aptX Low Latency\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBluetooth Wireless Range:\u003c\/strong\u003e At least 10 meters under suitable conditions\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBluetooth Antenna:\u003c\/strong\u003e External antenna, included\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBluetooth Pairing Reset:\u003c\/strong\u003e Dedicated rear-panel reset button\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eTotal Audio Output Types:\u003c\/strong\u003e 2\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHeadphone Output:\u003c\/strong\u003e 1 × 3.5mm stereo headphone jack\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eAnalog Preamplifier Output:\u003c\/strong\u003e 1 × stereo RCA pair\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHeadphone Impedance Compatibility:\u003c\/strong\u003e 32–300 ohms\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHeadphone Output Power at 16 Ohms:\u003c\/strong\u003e 300mW\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHeadphone Output Power at 32 Ohms:\u003c\/strong\u003e 250mW\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHeadphone Output Power at 250 Ohms:\u003c\/strong\u003e 50mW\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHeadphone Output Power at 300 Ohms:\u003c\/strong\u003e 40mW\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHeadphone Priority:\u003c\/strong\u003e Yes; RCA output is muted when headphones are connected\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eSignal-to-Noise Ratio:\u003c\/strong\u003e At least 103dB\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eDynamic Range:\u003c\/strong\u003e 104dB\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eFrequency Response:\u003c\/strong\u003e 20Hz–20kHz (±1dB)\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBass Control:\u003c\/strong\u003e Independent front-panel rotary control\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eTreble Control:\u003c\/strong\u003e Independent front-panel rotary control\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eVolume Control:\u003c\/strong\u003e Multifunction front-panel rotary knob\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003ePower Control:\u003c\/strong\u003e Press-and-hold multifunction knob\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eInput Selection:\u003c\/strong\u003e Front-panel multifunction knob\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eInput Indicators:\u003c\/strong\u003e Front-panel LED indicators\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eDSD Indicator:\u003c\/strong\u003e Dedicated front-panel indicator\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eTube Warm-Up:\u003c\/strong\u003e Approximately 15 seconds recommended before playback\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003ePower Requirement:\u003c\/strong\u003e DC 12V\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eIncluded Power Adapter:\u003c\/strong\u003e 12V DC power supply\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eEnclosure:\u003c\/strong\u003e Compact metal chassis with exposed vacuum tubes\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eTube Accessories:\u003c\/strong\u003e Decorative rings for both vacuum tubes\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eCompatible Speaker Systems:\u003c\/strong\u003e Powered speakers or passive speakers driven by an external amplifier\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBuilt-In Speaker Amplification:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eSpeaker-Level Outputs:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eStereo Speaker Pairs Powered Directly:\u003c\/strong\u003e 0\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eAnalog RCA Inputs:\u003c\/strong\u003e 0\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003ePhono Input:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBalanced XLR Input:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBalanced Headphone Output:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003e6.35mm Headphone Output:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eWi-Fi Connectivity:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eApple AirPlay:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eBuilt-In Network Music Streaming:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHDMI Inputs:\u003c\/strong\u003e 0\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eHDMI Outputs:\u003c\/strong\u003e 0\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003e12V Trigger Input:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003e12V Trigger Output:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eRemote Control:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eApp Control:\u003c\/strong\u003e No\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eManufacturer Warranty:\u003c\/strong\u003e 24-month limited warranty\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eIncluded Accessories:\u003c\/strong\u003e Fosi Audio GR40, 2 × 5654W vacuum tubes, 2 × decorative tube rings, 12V power adapter, Bluetooth antenna, and user manual\u003c\/li\u003e \u003c\/ul\u003e  \u003ch4\u003eWhat It's Great At\u003c\/h4\u003e \u003cul\u003e \u003cli\u003e\n\u003cstrong\u003eHigh-Resolution Digital Audio Conversion:\u003c\/strong\u003e The ESS ES9028Q2M DAC supports PCM up to 32-bit\/384kHz and DSD256 through USB, making it an excellent foundation for enjoying high-resolution music files.\u003c\/li\u003e  \u003cli\u003e\n\u003cstrong\u003eClassic Vacuum Tube Sound:\u003c\/strong\u003e Two replaceable 5654W tubes bring the distinctive harmonic character of tube preamplification to headphone listening and compatible stereo audio systems.\u003c\/li\u003e  \u003cli\u003e\n\u003cstrong\u003eVersatile Digital and Wireless Connectivity:\u003c\/strong\u003e Bluetooth 5.1, USB-C, optical, and coaxial inputs accommodate computers, smartphones, CD transports, televisions, and other compatible digital music sources.\u003c\/li\u003e  \u003cli\u003e\n\u003cstrong\u003eDedicated Headphone Amplification:\u003c\/strong\u003e A 3.5mm headphone output delivers up to 250mW into 32 ohms and supports compatible headphones from 32 to 300 ohms, with headphone-priority switching for convenient private listening.\u003c\/li\u003e  \u003cli\u003e\n\u003cstrong\u003eStereo Tube Preamplifier Functionality:\u003c\/strong\u003e A dedicated stereo RCA output allows the GR40 to connect to powered speakers or external amplifiers, bringing its DAC and vacuum tube sound character into a larger Hi-Fi system.\u003c\/li\u003e  \u003cli\u003e\n\u003cstrong\u003eCustomizable Sound and Tube Design:\u003c\/strong\u003e Independent bass and treble controls, user-replaceable vacuum tubes, and convenient front-panel operation make it easy to personalize your listening experience.\u003c\/li\u003e \u003c\/ul\u003e  \u003ch4\u003eFAQ Section\u003c\/h4\u003e  \u003cp\u003e\u003cstrong\u003eQ: What is the Fosi Audio GR40 used for?\u003c\/strong\u003e\u003cbr\u003e A: The Fosi Audio GR40 is a combined digital-to-analog converter, vacuum tube stereo preamplifier, and headphone amplifier. It converts digital audio from Bluetooth, USB, optical, and coaxial sources into analog sound for compatible wired headphones or a stereo system connected through its RCA outputs.\u003c\/p\u003e  \u003cp\u003e\u003cstrong\u003eQ: What audio inputs and outputs does the Fosi Audio GR40 have?\u003c\/strong\u003e\u003cbr\u003e A: The GR40 features four selectable audio input types: Bluetooth 5.1, USB-C, optical digital, and coaxial digital. It offers two analog output types: one 3.5mm stereo headphone output and one stereo RCA preamplifier output. It does not include analog RCA inputs, balanced XLR connections, or speaker-level outputs.\u003c\/p\u003e  \u003cp\u003e\u003cstrong\u003eQ: Does the Fosi Audio GR40 support Bluetooth music streaming?\u003c\/strong\u003e\u003cbr\u003e A: Yes. The GR40 features Bluetooth 5.1 with SBC, AAC, aptX, aptX HD, and aptX Low Latency codec support. This allows wireless music playback from compatible smartphones, tablets, and computers, while aptX Low Latency can help reduce audio delay when used with a compatible transmitting device. The GR40 does not include Wi-Fi or independent network streaming services.\u003c\/p\u003e  \u003cp\u003e\u003cstrong\u003eQ: Can the Fosi Audio GR40 play high-resolution audio?\u003c\/strong\u003e\u003cbr\u003e A: Yes. The GR40 includes an ESS ES9028Q2M DAC supporting PCM audio up to 32-bit\/384kHz and DSD256 through its USB input. Actual playback resolution depends on the connected source, connection type, software, and audio format.\u003c\/p\u003e  \u003cp\u003e\u003cstrong\u003eQ: How much headphone power does the Fosi Audio GR40 deliver?\u003c\/strong\u003e\u003cbr\u003e A: The GR40 delivers 250mW into 32 ohms, 50mW into 250 ohms, and 40mW into 300 ohms, with a published measurement of 300mW at 16 ohms. Fosi Audio specifies a recommended headphone impedance range of 32 to 300 ohms, making it suitable for a variety of compatible headphones.\u003c\/p\u003e  \u003cp\u003e\u003cstrong\u003eQ: Can I use the Fosi Audio GR40 as a tube preamplifier?\u003c\/strong\u003e\u003cbr\u003e A: Yes. The GR40 features stereo RCA preamplifier outputs for connection to compatible powered speakers, integrated amplifiers, or dedicated power amplifiers. This allows you to use its DAC and vacuum tube preamplifier stage as part of a larger Hi-Fi system. It cannot directly power passive speakers.\u003c\/p\u003e  \u003cp\u003e\u003cstrong\u003eQ: Can headphones and RCA outputs play simultaneously?\u003c\/strong\u003e\u003cbr\u003e A: No. The GR40 uses headphone-priority output switching, meaning the rear stereo RCA outputs are automatically muted when headphones are connected. To resume playback through connected speakers or an external amplifier, disconnect the headphones from the front-panel jack.\u003c\/p\u003e  \u003cp\u003e\u003cstrong\u003eQ: Can I replace the vacuum tubes in the Fosi Audio GR40?\u003c\/strong\u003e\u003cbr\u003e A: Yes. The GR40 includes two replaceable 5654W vacuum tubes. Electrically compatible replacement models include EF95, 6AK5, 6AK5W, 403A\/403B, and selected 6J-series tubes. Always power off the unit, disconnect its power supply, and allow the tubes to cool completely before replacing them.\u003c\/p\u003e","brand":"Fosi Audio","offers":[{"title":"Default Title","offer_id":62887307837599,"sku":"FOS-GR40-BLK","price":119.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0495\/6910\/4031\/files\/e79a8e65-e147-497e-9c5e-d859066f02be.jpg?v=1791574389","url":"https:\/\/listenup.com\/products\/fosi-audio-gr40-tube-dac-headphone-amplifier-preamplifier","provider":"ListenUp","version":"1.0","type":"link"}