Little Bear B4-X

Product Price
Terms & conditions

Free standard shipping to most countries

Free express shipping on orders over $270*. Enjoy free tax and duty paid to most countries. Please refer to our shipping FAQ to see if you apply.

Covid-19 Shipping Delay Notice

Shipping may be delayed due to covid-19 depending on your country regulations.
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Authenthic Products

Linsoul Audio is the authorized distributor. All products are authentic and genuine.

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Worldwide Free Shipping

We are located in China but send our products worldwide for free. T&Cs apply.


1 Year Warranty

We provide 1 year warranty for the all products except the cables*.

The Difference Between B4 and B4-X

B4-X is a dual-mono balanced version. Its left and right channel are amplified by independent components, and power supply, tubes, and op amp are all independent and symmetric. So the degree of sound separation is higher than B4.

B4-X adopts 2 groups of independent power supply(+12V and -12V) for 2 op amps, less mutual effects and can drive 300Ω headphones.

The circuit adopts dual op amp parallel output, with higher output power.
B4-X has 3.5mm and 2.5mm 2 kinds of output interface, suitable for most of balanced and standard headphones.

Mini Size and Unique Design

Built-in tube makes you have a tube amplifier which can be held by one hand, convenient to carry and can enjoy HiFi music everywhere. Full, delicate and soft sound: warmer than transistors, independent op amp and power supply inhance the SNR and degree of separation, less interplay and higher sound quality.

With Built-in Battery Protection Circuit

Battery lets your listening feast without time limitation. It can't be turned on during charging and will power off automatically after fully charged, and charger LED will turn to green.

High-end Making Material and Craft

Using gold-plated socket, original nichicon electrolytic capacitor, original DALE resistors and precision ring resistance.


Coming soon...


Coming soon...

Customer Reviews

Based on 4 reviews
Very good

Excellent sound.

Paweł Karwot
Little bear b4-x

It's working fine, can drive even 300 Ohm headphones. Fine little device

Dimitry R.
Portable Tubes on Steroids - Little Bear B4-X with Burson V6 Vivid

Review of Little Bear B4-X portable tube amp modded with Burson V6 Vivid opamps and silicone o-rings:

O-rings are easy to put on. Just slide them gently as far low onto the tubes as possible before they can be moved down no longer due to other components. Opamp swap requires somewhat more massaging. First, the plastic window in B4-X has to go as V6’s are tall. It’s easy to get it out without breaking since it’s glued to the case – just gently push on it until it starts to come off. Unfortunately, even with the window removed, there’s still about 1-2mm not enough space left to keep V6’s at 90 straight vertical angle. Therefor, when putting the top of the case back on, I left a little bit of extra space for the opamps but not screwing it fully in – and vice versa, I left extra space on the opposite side for the bottom of the case. With that, opamps are almost vertical at about 85 degree angle. They sit it fairly flush, there are no disconnects. In terms of storage, I use a tupperware container to keep dust from getting inside since the window is gone.

With poopy stock NE5532 opamps (retail under $1), I already hear a warm, liquidly, syrupy mid-centric sound that adds pleasant distortion which makes music fuller and richer. It’s quite enjoyable to begin with, however on technical level there’s poor vertical soundstage extension both ways while instrument separation on the stage lacks room and airiness. Staging and congestion get improved dramatically with V6 Vivids. We get better dynamics, transients, decay, slam as things get tighter while maintaining the same pleasant, musical, analogue distortion. Driving power seems to increase as well, as same volume level can be achieved at lower volume knob setting.

Generally speaking, the noise floor is high. If there’s no music playing, there will be audible noise on 99% of dynamic and BA headphones and earphones with impedance of 32 ohm and below. Even with fancy op-amps, B4-X best suited for high impedance drivers as well as for planar magnetic drivers. There’s no difference in sound between 3.5mm and balanced 2.5mm outputs. Balanced output sounds a slightly bit louder.

Smabat ST-10s Gold – featuring high impedance of 150ohm, B4-X does these earbuds justice. Cold mids are warmed, high mids peak is smoothed, while impressive bass is presented in high resolution and powerful slam.
Monolith M570 – these open-backed headphones are driven by planar magnetics. Little Bear adds warmness and richness that makes them sound less bright and more powerful down-low. Already highly-detailed mids get more musical.
Sennheiser HD6XX – there’s enough power at hand to drive this 300 ohm legend. It’s all about the mids with this combo, sounding super smooth yet textured. Vocals and associated note decay are amazingly yummy.
Hifiman HE560 – there’s not enough juice in the bank. Little Bear starts producing fart-like noises when trying to increase volume to decent levels.

Aune B1s – it can push a whopping 6.5 Vrms through its single-ended output. It does have more current on-hand which makes it sound more powerful and authoritative. Mids, especially low mids, are congested in comparison as B4-X with V6 Vivids really improves and showcases excellent separation and airiness in sound.
Fiio E12 – it can go louder than B4-X, that’s certain. However, E12 sounds somewhat coarse in comparison which negatively impact timbre. Bass slam is also better with Bass Boost on, but bass doesn’t sound as musical as on the Little Bear.

All-in-all for about $250 which is the approximate total cost of Little Bear B4-X, V6 Vivid opamps x2, and silicone o-rings, we get a high-quality transportable portable amp that is excellent to use with headgear that is relatively medium-hard to drive. It sounds much more analogue and musical than what most sources released nowadays do, since it doesn’t try to go for best SNR etc, it’s all about music enjoyment!

Matthew N
Powerful Little Beast

I'm not an audiophile person, but I enjoy music and iem's, but what I can say about this tube amp, it works! It amplifies and it improves the sound signature on almost all of my iem's, and it being balanced(2.5jack) really makes everything much better, I own about 15 iem's but the ones I really notice a major improvement in sound over just plugging it straight into the pc are the Shozy Form 1.1 and the Semkarch CNT1, the bass hits harder, the clarity is improved, and it warms everything up and smooths things out, kinda hard to explain, but I notice it. It gets slightly warm, overall it's a nice entry step into tubes without blowing alot of money to see if this is a flavor of something you might like. The only downfall, it has to be recharged after about 4 hours of using, but that goes without saying as these have a pretty good output of power.

Our Shipping Process

If everything goes right our system will automatically generate your order and send you a confirmation email. If you don't receive the confirmation email please double-check that it wasn't automatically stored in your spam or promotions folder.

3 Working Days*

Most of the items you see are in stock and ready to be shipped after 3 working days. If you plan to order a custom (Design or Fit) product, a pre-order, or a made to order item processing times may change on item to item basis.

Standard Shipping
15 to 30 Days.

Standard shipping is offered free worldwide for orders under $269 USD (with some exceptions), but please consider that delivery times may vary considerably depending on your country, up to 90 Days.

Express Shipping
3-6 Working Days.

Most items over $270 include free express shipping (DHL or similar). If your order total is under $270 you can manually add Express Shipping at the checkout page for $15.00 - $35.00USD

World-Wide Shipping

Shipping FAQ

Which countries do you ship to?

We are generally able to ship to most countries via Express Shipping, and many countries via Standard Shipping. You may clarify this with our team to check whether Standard Shipping is available to your country.

We cannot ship to addresses that are "PO boxes or APO/FPO".

*Note: Generally, we can only do Selected Shipping to India and Russia. We can only do Express Shipping to Africa, Argentina, Hawaii, Kuwait, Mauritius, Montenegro and Sri Lanka, to name a few.
This may be subjected to changes due to unpredictable issues such as Covid, war, and etc.

How much does shipping cost?

We have two shipping methods - Standard Shipping and Express Shipping.

Standard Shipping is free for most countries, while Express Shipping is 15-35USD depending on your country. If your order is over 270USD, Express Shipping is free*. 

*This applies for most countries. However, large items such as headphones and desktop DAC/AMPs (e.g. HarmonicDyne G200, MUSICIAN MDP-2, and etc.) are excluded.

Shipping fees exclude import taxes or processing fees that may be applicable for your country. Linsoul is not responsible for such fees. Should you refuse to pay the tax/customs fees, shipping fees will still be deducted from the amount paid for the two-way freight charges. The cost of the freight charges may be more than the amount reflected on your order due to tax and other miscellaneous fees.

Some parcels claimed to be “returned to the seller” may be destroyed by the post office or customs officers when buyers refuse to accept their parcels or fail to pay for their taxes. No refund will be processed for such cases.

Standard Shipping via YunExpress is a tax-inclusive option for some countries. However, Linsoul will not be responsible for additional administrative or handling fees charged by your local courier company or customs. Please kindly check this with your local customs.

For certain remote areas, there may be additional charges via Express Shipping. We will contact you if there is a need to make additional payments. 
Please contact us before placing an order, should you have any queries regarding shipping.  

How long does it take to receive the order after it is placed?

For in-stock products, your order will be shipped within 3 working days. You may check with our staff regarding the in-stock status of any products. 

Customized items will take a longer time. Please contact our staff for more information.

On normal non-sale days, once your parcel has been shipped out:

  • For Standard Shipping, it takes about 2-4 weeks for items to be delivered after shipping out. For some countries, it might take up to 2-3 months, depending on your country, its customs and other factors.* The duration for transit is something beyond our control. Linsoul will not be making refunds for such cases. Please consider an upgrade to Express Shipping or keep the waiting time in mind.
  • For Express Shipping, it takes about 3-7 days for items to be delivered after shipping out.

*Note: Timings might be affected due to festive seasons or other unforeseen circumstances

What happens if the parcel has been shipped but not delivered?
  1. First, kindly contact your local courier using the local tracking number.
    If your parcel were to be in transit for at least 3 months, it may have been lost in transit.
    For orders below $50USD, you may either opt for a one-time reshipment of parcel OR a full refund of the amount paid in cash via PayPal/Credit/Debit card.
    For orders above $50USD, we will only process a 50% refund of your order paid in cash via PayPal/Credit/Debit card. Should there be any concern about Standard Shipping, you are encouraged to opt for DHL Express Shipping instead.
  2. Customers are to bear the consequences and fees incurred, if the parcel was undelivered due to any of the following situation:
    • Wrong address or phone number provided by recipient
    • Recipient was uncontactable when courier company contacted
    • Refusal to sign for the package by recipient
    • Lost or damaged parcel because recipient opted for “no-signature delivery”
    • Refusal to pay for the local tax/processing fee by recipient
    • Refusal to provide supporting documents for custom clearance by recipient
Who will pay for the import tax/custom fees

Customers have to bear any form of custom/import/processing fees that are applicable for your parcel.

Should you be unwilling to pay for the fees and reject the delivery of the parcel, you will still have to pay for the shipping cost. Linsoul will only refund the amount of your order after deducting the two-way shipping fees incurred.

How do I get help for my order?

Cancellation or/and modification of orders can only be done manually via our staff, provided that our Warehouse Team has not processed your order.
As our Support Team might not be available during non-working days and weekends, please place your order wisely.
Should you really need to cancel or/and modify your order after purchase, please contact us via our support email ( or website chat. We will help you with the changes if that could be done.

In general, upon receiving your parcel, please confirm the contents of the package and ensure that the package is in good condition before signing for it. All customers are strongly advised to take an unboxing video of their parcel and packaging when opening their parcels and products.

For faulty/missing items, please send an email to for after-sale services. The following details are required.
1) Send an email to with an appropriate Subject Title 
2) Provide your order number and state the issue clearly
3) Attach photos and videos to show that your product is faulty/missing. Shipping details on the parcel packaging have to be clearly visible.

If the photos/videos provided are insufficient to prove the stated issue, we will enquire more. Once the issue has been confirmed, we will arrange for a replacement, partial refund or a full refund (where applicable). For incorrect products, Linsoul reserves all rights in deciding whether you need to return the incorrect item or not. Please kindly contact us via email first. Our team aims to review your email within 3 working days.

For other queries, the fastest way to contact us is via our website or Discord

Linsoul Audio will not be responsible for parcels that have been damaged during the transit process.

Do I get tracking details for my order?

After placing an order, you will receive the order confirmation email. After your order has been shipped out, you will also receive a tracking email. You can track your order via the tracking number online. Should you not have received the emails or face any difficulties tracking your order, please kindly contact us for support.

For more than 1 orders placed under the same account and shipping address, Linsoul will automatically combine the orders and ship them out via one tracking number. Should you have special requests to have the orders shipped separately, please kindly contact us via Discord or our website's chat. We will do our best to help.

What shipping companies do you use?

We collaborate with these courier companies:
Standard Shipping: 4PX, UBI, NinjaVan, and Yun Express
Express Shipping: DHL Express, FedEx and SF Express

Last updated: 1 November 2022

Little Bear B4-X
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