Includes all taxes
Fosi Audio Phono Preamp for Turntable Phonograph Preamplifier With Vacuum Tube Amplifier HiFi BOX X4
Notice:
1.Due to limited availability of vacuum tubes, we will randomly ship either 5725W or 6J1 vacuum tubes.
2.BOX X4 is only a preamplifier, not amplifier, can not be connected with passive speakers directly, If you need connect BOX X3 with passive speakers, you need to connect it with an amplifier then connect the amplifier with your passive speakers.
Features:
1. Tube MM Phono Preamplifier: The BOX X4 phono preamp supports 3.5MM AUX and MM turntable input, converting phono signals to Line Level with low-frequency noise removal using high-quality components and low-noise integrated circuits. Protect your turntable with the grounding post feature
2.Tube Headphone Amplifier & Preamplifier: The Fosi Audio BOX X4's versatile design includes a 3.5MM AUX headphone and RCA output, offering a range of usability beyond expectations
3.Applicable Vacuum Tube Model: 6K4/6J1/6J4/GE5654/6AK5/66*In vacuum tubes, etc. Achieve a customized stereo system by replacing vacuum tubes. With different tubes producing unique sounds, it's a DIY opportunity worth exploring
Highlight:
Model: BOX X4
Power Adapter Output: 12V
Product Adapter Input Voltage Range: AC 100V - 240V
Output Voltage Level: 1kHz and 650mV
SNR ≥ 70dB
THD ≤ 0.1%
Frequency Response: Standard RIAA
Product Weight: 0.71 lb/320g
Product Dimensions: 3.97x4.72x1.37 inch (10.09*12*3.5 cm)
Input Mode: MM turntable input +3.5mm AUX
Output Mode: RCA output + 3.5mm headphone output
Applicable headphone types: 16 Ω - 300 Ω
Package Include:
*Box X4 Phono Preamp x1
*5725W/6J1 Vacuum Tubes x2
*12V Power Adaptor x1
*User Manual x1
Q1:Can the headphone and RCA outputs be used simultaneously?
Yes. When both the 3.5mm headphone output and RCA output are connected, sound will be output through both the headphones and RCA connectors.
Q2:Can the BOX X4 be used with an MC cartridge?
NO.The BOX X4 is designed specifically for use with MM cartridges. However, our upcoming model, the BOX X5 is compatible with MC cartridges.





Payment Policy – BILLIONS BIRDS
At BILLIONS BIRDS, we are committed to providing a safe, secure, and seamless payment experience for our customers.
1. Accepted Payment Methods
We accept the following payment options:
Major Credit & Debit Cards (Visa, MasterCard, American Express)
Secure Online Payment Gateways (such as PayPal, Stripe, or other providers available at checkout)
Any additional payment methods displayed during checkout
All payments must be completed in full at the time of purchase.
2. Secure Transactions
All transactions are processed through encrypted and secure payment systems to protect your personal and financial information. We do not store your full payment details on our servers.
3. Currency
Prices are displayed in the currency indicated on the website. If you are purchasing from another country, your bank may apply currency conversion fees.
4. Order Confirmation
Once your payment has been successfully processed, you will receive an order confirmation email containing your purchase details.
5. Failed or Declined Payments
If your payment is declined, please verify your billing information or contact your bank. Orders will only be processed after successful payment confirmation.
6. Fraud Prevention
BILLIONS BIRDS reserves the right to cancel or refuse any order if fraud or unauthorised activity is suspected.
Delivery Policy – BILLIONS BIRDS
At BILLIONS BIRDS, we are dedicated to delivering your orders safely and efficiently.
1. Order Processing
All orders are processed within 1–3 business days after payment confirmation. Orders are not processed or shipped on weekends or public holidays.
2. Shipping Times
Estimated delivery times vary depending on your location:
Domestic Shipping: 3–7 business days
International Shipping: 7–15 business days
Please note that delivery times are estimates and may vary due to customs procedures, carrier delays, weather conditions, or other unforeseen circumstances.
3. Shipping Costs
Shipping fees are calculated at checkout based on your location and selected shipping method. Any customs duties, taxes, or import fees are the customer's responsibility.
4. Tracking Information
Once your order has been shipped, you will receive a confirmation email with tracking details (if available) so you can monitor your package.
5. Delivery Issues
If your order is delayed, lost, or arrives damaged, please contact us within 7 days of the expected delivery date. We will work with the shipping carrier to resolve the issue as quickly as possible.
6. Incorrect Shipping Information
Customers are responsible for providing accurate shipping details at checkout. BILLIONS BIRDS is not responsible for orders shipped to incorrect addresses provided by the customer.
Refund Policy – BILLIONS BIRDS
At BILLIONS BIRDS, customer satisfaction is our top priority. If you are not completely satisfied with your purchase, we’re here to help.
1. Return Eligibility
You may request a return within 14 days of receiving your order. To qualify for a return:
The item must be unused, unworn, and in the same condition as received.
The item must be in its original packaging.
Proof of purchase (order confirmation or receipt) is required.
Certain items may not be eligible for return, including clearance items, gift cards, or personalised/custom products.
2. Non-Refundable Items
The following items are non-refundable:
Final sale or discounted items
Gift cards
Items damaged due to misuse, negligence, or improper care
3. Return Process
To initiate a return, please contact our customer support team with your order number and reason for return. If your return is approved, you will receive instructions for returning the item.
Unless the item is defective or incorrect, customers are responsible for return shipping costs.
4. Refund Processing
Once we receive and inspect your returned item:
We will notify you of the approval or rejection of your refund.
If approved, the refund will be issued to your original payment method within 5–10 business days.
Please note that banks or payment providers may require additional time to process refunds.
5. Damaged or Incorrect Items
If you receive a damaged, defective, or incorrect item, please contact us within 7 days of delivery and provide clear photos of the product and packaging. We will arrange a replacement or full refund at no additional cost.
6. Late or Missing Refunds
If you have not received your refund:
Check your bank account again.
Contact your credit card company or payment provider.
If the issue persists, don't hesitate to contact our support team for assistance.
Share your thoughts with other customers