The Fosi Audio GR70 is a premium quad-tube headphone amplifier and preamp that blends the classic charm of vacuum tube audio with the precision of modern engineering. Featuring two 5654W and two 6Ж4 replaceable vacuum tubes, it delivers a rich, warm, and immersive listening experience that brings music to life.
Its dual-stage amplification ensures exceptional clarity and tonal depth—5654W tubes boost voltage for smooth mids and highs, while 6Ж4 tubes handle power amplification for dynamic, textured bass. Whether you’re pairing with over-ear headphones, IEMs, or a full Hi-Fi system, the GR70 adapts effortlessly.
With low and high impedance modes (16Ω–300Ω), multiple headphone outputs (6.35mm & 3.5mm), and RCA input/output for preamp functionality, the GR70 fits seamlessly into any audio setup. The large top-mounted volume knob, bass & treble tone controls, and dual-side ventilation make it both functional and stylish.
Built from CNC-machined aluminum alloy, this compact yet powerful amp outputs up to 300mW @ 32Ω, offering a signal-to-noise ratio ≥97dB for clean, distortion-free sound. The Fosi Audio GR70 is the perfect choice for audiophiles seeking authentic tube warmth without compromising detail or precision.
Specifications
Model: Fosi Audio GR70 Type: Tube Headphone Amplifier & Preamp Tubes: 2 × 5654W, 2 × 6Ж4 (replaceable) Input: RCA Outputs: RCA, 6.35mm, 3.5mm headphone jacks Max Power Output: 300mW @ 32Ω Power Input: DC 12V/3A Headphone Impedance: • Low Mode: 16Ω–120Ω • High Mode: 120Ω–300Ω Output Voltage (RCA): 1.2V SNR: ≥97dB Controls: Volume knob, bass & treble tone controls, high/low impedance switch Body Material: CNC-machined aluminum alloy Design Features: Dual-stage amplification, dual-side ventilation, compact form factor
Model: Fosi Audio GR70
Type: Tube Headphone Amplifier & Preamp
Tubes: 2 × 5654W, 2 × 6Ж4 (replaceable)
Input: RCA
Outputs: RCA, 6.35mm, 3.5mm headphone jacks
Max Power Output: 300mW @ 32Ω
Power Input: DC 12V/3A
Headphone Impedance:
• Low Mode: 16Ω–120Ω
• High Mode: 120Ω–300Ω
Output Voltage (RCA): 1.2V
SNR: ≥97dB
Controls: Volume knob, bass & treble tone controls, high/low impedance switch
Body Material: CNC-machined aluminum alloy
Design Features: Dual-stage amplification, dual-side ventilation, compact form factor
In The Box
GR70 Main Unit *1
6AC7 Vacuum Tubes *2
5654 Vacuum Tubes *2
Tube Protection Covers *2
12V/3A Power Supply *1
User Manual
Warranty Period: 1 Year from the date of Invoice
Covered: Manufacturing Defects Only
Warranty Form: https://www.theaudiostore.in/pages/warranty-claim-form
Cable: 1-month warranty only for manufacturing defects only
Fosi Audio is a dynamic brand dedicated to providing the most comprehensive range of Hi-Fi audio products in the market. We cater to passionate audiophiles by offering Hi-Fi products, DIY kits, and expert guidance, ensuring an immersive audio experience. Beyond a mere transaction, we foster enduring relationships with our clients, supporting them throughout their audio journey.
Our diverse product lineup includes the Hi-Fi power amplifier, pre-amplifier, headphone amplifier, DAC, music player, Bluetooth receiver, DIY board, DIY chassis, and an array of DIY kits. These meticulously crafted offerings embody our commitment to exceptional sound quality and innovation.
Established in China in 2017, Fosi Audio was founded by a team of devoted audiophiles. Our products have gained significant popularity within the Chinese DIY audio community, amassing a large and dedicated following. To expand our reach beyond borders, we launched this website in 2017 and began offering a selection of products on Amazon under the name "Fosi audio." However, please note that many of our outstanding products are not yet available on this website or Amazon. If you cannot find what you're looking for, simply reach out to us via email, and we will be delighted to assist you in finding the perfect product to meet your needs.
At Fosi Audio, we are not just a brand; we are your partner in achieving audio excellence. Join us on this immersive sonic journey and experience the true essence of Hi-Fi audio.
At the price, can't complain.
Perfect sturdy piece to carry(not in pockets) anywhere
Truthear Hexa fits perfectly.
EarAudio In-Ear Monitors (IEM), Earphones Carry Case
11/13/2025
Anjan Prasad
Great purchase in this price range
DAC sounds perfect when you connect it with laptop or PC
has a less sound when you play with Smartphone.
Other than this the IEMs are great
Great fit to ears
ROSESELSA AURORA Ultra IEM
11/10/2025
Anonymous
This DAC is awesome and a perfect value addition to my IEM
This DAC is awesome and a perfect value addition to my IEM. It enhances the quality of the audio and make it a bit loader as well. Buying and its a must have accessory for the audiophiles.
AUDIOCULAR SPARK Hi-Res Portable DAC Dongle CX31993 + MAX Amp
11/10/2025
Kevin Dedhia
Heavenly
Powerful, stylish, worth the price, good mic quality, the best in the range!
KZ Castor Pro IEM With Mic
11/09/2025
Kevin Dedhia
High quality stuff
Powerful performance with good looks
AUDIOCULAR SPARK Hi-Res Portable DAC Dongle CX31993 + MAX Amp - Black
11/09/2025
Kevin Dedhia
High quality carry case
I like the simple design without any text. The material is good. The size is perfect for carrying DAC - IEM - any other accessory.
EarAudio In-Ear Monitors (IEM), Earphones Carry Case
11/09/2025
Prakarsha Xx
This iem is my daily driver for office
Very easy to carry in sleek silicon pouch that you get with the iem.
I dont use it to listen to music but for teams and zoom calls in office .very handy
7HZ G1 Type-C IEM With Mic
11/09/2025
Prakarsha Xx
Works perfectly as advertised
Using this balanced cable with my fiio k11 r2r to drive headphones like edition XS
EarAudio Headphone Replacement Cable
11/09/2025
Padmapriyan
Underated
Such a great one on this price range. Highly recommend if the budget is 4-5k
KEFINE Klean IEM
11/08/2025
Balakrishna Badveli
Worth every rupee you spend on this product
I have not expected this great audio quality but after hearing the sound this is fabulous and no words to express.
Great product in this price range.
ROSESELSA AURORA Ultra IEM
11/06/2025
Jigar Patel
Balanced audio
i would say it is best for who likes music and vocal not for the base lover.
KZ EDX Pro X Wired IEM With Mic
11/06/2025
Divesh sutar
Best quality and enhance sound volume compare to
Best quality and enhance sound volume compare to one plus and iphone type c converter
AUDIOCULAR SPARK Hi-Res Portable DAC Dongle CX31993 + MAX Amp
11/05/2025
Anonymous
Real good iems
Love these, u shaped sound signature but pains my ears after 2 hours of listening.
Dunu Titan S2 IEM
11/03/2025
Anonymous
The IEM's have a decent balanced V shaped profile & the manual EQ settings are quite useful
The IEM's have a decent balanced V shaped profile & the manual EQ settings are quite useful.
AUDIOCULAR X KZ Castor Pro X Type-C IEM With Mic
11/03/2025
Sagarpatel
If you listen to music that's supposed to really H-I-T, this is the one for you.
After my first pair, the Oriveti OD200 (which I loved!), I grabbed the Martilo as my second set, and wow, I finally get what people mean by basshead. Guys, these are unreal. If you listen to music that's supposed to really H-I-T, this is the one for you.
Sound Breakdown
The Bass is the star: It literally shakes my eardrums. We're talking deep, physical sub-bass rumble, not the muddy, boomy kind. It feels like having a huge subwoofer in your head. It hits hard but stays clean and super fast, which is critical.
Mids are surprisingly clear: I was worried the bass would swallow up the vocals (Mids), but they stay right up front. My favorite singers sound crisp! You get great separation, letting you pick out instruments even when the bass is going crazy.
Treble is sparkly and quick: I think the planar driver is what makes the high notes (Treble) sound so detailed. It adds enough "air" to the sound and keeps the whole picture from feeling dark.
The design is awesome, they look like cracked lava rock, and they are pretty comfortable even though they look a bit chunky.
Only 1 downside for me was the eartips, it could be more comfortable given the price tag of this IEMs. I'm using stock eartips of my another IEMs (Oriveti OD 200) which is surprisingly comfortable.
Final Takeaway
If you are moving up from entry-level and want to know what truly clean, hard-hitting bass sounds like, get these. It’s an easy, near-endgame fun set for people who love bass-heavy genres like EDM and Hip-Hop. Go listen to them!
Punch Audio Martilo IEM
11/01/2025
STAY TUNED ON EVERY PLATFORM
Brand Warranty
100% Original products with brand warranty
7 Days Replacement
On all orders*
Fast & Free Shipping
Ships in 24 Hours*
Secure Payments
Visa, Mastercard, EMI, Net Banking, UPI, BHIM, Wallet's
Opens in a new window.
Anonymous
It's a solid iem
It's a solid iem, has amazing sound quality compared to my old tws, and has good packaging too.
TANCHJIM Bunny Type-C DSP Plug with Mic IEM
Anonymous
Great details
Great details.
KEFINE Delci AE IEM
Anonymous
Great looking cable
Great looking cable and sounds good as well
AUDIOCULAR C04 16-Core Silver-Plated Cable with Balanced 4.4mm Jack For IEMs
Ritvik singh
Sturdy
At the price, can't complain.
Perfect sturdy piece to carry(not in pockets) anywhere
Truthear Hexa fits perfectly.
EarAudio In-Ear Monitors (IEM), Earphones Carry Case
Ajith Suresh
Very Good Product
i was using it for a long time and it's so nice
MOONDROP SPACE TRAVEL True Wireless Earbuds
Kaustubh Mudgale
This IEMs delivers excellent sound across all music genres and is used daily
This IEMs delivers excellent sound across all music genres and is used daily. The unboxing experience is premium. However, a minor issue has been identified: the right-side IEM produces a subtle noise when tapped while worn, which may indicate a manufacturing defect.
Truthear x Crinacle Zero:BLUE2 IEM
Anonymous
The build quality and cable is excellent and compact.
AUDIOCULAR SPARK Hi-Res Portable DAC Dongle CX31993 + MAX Amp
Jarvis Dhali
EZ EDX pro
I recently purchased the KZ EDX Pro in-ear monitors, and I must say I’m really impressed with the performance they deliver, especially for the price range. The sound quality is clear, detailed, and well-balanced with a nice punch in the bass, making it great for gaming, music, and everyday use.
The design and comfort are excellent — they fit perfectly in the ears and don’t cause any discomfort even after long hours of use. The build quality feels premium, and the detachable cable adds extra convenience and durability.
When it comes to gaming (like BGMI or other FPS titles), the sound separation and footstep clarity are surprisingly good for this budget segment. You can easily detect enemy movements and directions, which gives a competitive edge during matches.
Overall, the KZ EDX Pro offers outstanding value for money. It’s a solid choice for gamers, music lovers, and anyone looking for clear sound without spending too much. Highly recommended
KZ EDX Pro X Wired IEM With Mic
Sourav
Good stuff
Good stuff. As my first IEM, I'll have to say that I am not a bit disappointed.
KZ EDC PRO Wired IEM With Mic
Jayesh Mann
Best Budget IEM - blind buy recommendation
you can tune the dsp version using the tanchjim app if it's not upto your liking, which is highly unlikely.