Douk Audio ST-02 Integrated Tube Amplifier Review

The Douk Audio ST-02 is an integrated HiFi amplifier — a single chassis combining a DAC, a stereo power amplifier and a headphone amplifier. At $239.99 it sits in the budget integrated-amp category, an evolution of the ST-01 PRO built around a TPA3255 amplifier chip with a 300W x 2 headline; the page's own table gives 107W+107W into 4 ohms with the 36V/6A adapter in the box. Post-Filter Feedback (PFFB) is used to keep the frequency response more consistent across different speaker loads.

For 2.1 setups, an adjustable 20-230Hz high-pass filter reduces deep-bass load on the main speakers while a 150Hz low-pass SUB OUT feeds a powered subwoofer for a cleaner, better-integrated low end. On the input side you get Bluetooth 5.4, PC-USB, optical, coaxial and RCA, plus direct lossless playback from USB drives — covering both digital and analog sources without a separate DAC.

The tube section is a custom ECC83 stage running at 180V for more composed dynamics, with large VU meters whose sensitivity adapts across signal levels. Tone shaping runs to plus/minus 9dB for bass and treble with a BYPASS option for a more direct path, and four socketed NE5532 op-amps let you tune the sound later. Headphones connect through 3.5mm or 4.4mm jacks, and headphone/speaker modes can be switched between. A high-clarity TFT, top-panel controls, remote and an aluminum-alloy chassis round out the hardware. It is a pre-sale listing, and the page says shipping to all regions starts December 1.

Specifications

How it compares

The ST-01 PRO Bluetooth Tube Amplifier review ($109.99) is the model the ST-02 page says it evolved from, and $130.00 cheaper. The ST-02 page lists Bluetooth 5.4 (against 5.0), a TPA3255 power chip (the ST-01 PRO page says TPA3250), a 150Hz SUB OUT with an adjustable 20-230Hz high-pass, two headphone outputs, a TFT display and a lower printed distortion figure with a higher printed SNR (THD+N of 0.02% and SNR of 103dB or better, against THD of 0.07% and SNR of 98dB or better; THD+N and THD are different measures). The ST-02's headline is 300W x 2, but its own table gives 107W+107W into 4Ω with the 36V/6A adapter in the box, close to the ST-01 PRO's 100W+100W rating; only a 48V/10A supply reaches 250W+250W, and the page lists no such adapter. The extra money buys connectivity, a 2.1 crossover and headphone outputs more than power.

The Douk Audio T6PRO TPA3255 Tube Amplifier review ($139.99) uses the same TPA3255 chip and a similar tube stage for $100.00 less (its $139.99 option has no adapter), with Bluetooth 5.1, two RCA inputs, a 3.5mm AUX input and a pre-out, but no digital inputs, no headphone output and no subwoofer filter. Its page offers the unit without an adapter or with a 32V/5A or 48V/5A one, and its table gives 78W+78W, 120W+120W and 250W+250W into 4Ω for 32V/5A, 48V/5A and 48V/10A; the ST-02 box lists a 36V/6A adapter. The Nobsound DA3 Bluetooth Tube Amplifier review ($189.99) costs $50.00 less than the ST-02 and is rated 35W x 2 at 4Ω; it has a headphone jack and a pre-out, but its page prints THD of 1% and SNR of 70dB. For a 2.1 system with a powered subwoofer and headphones, the ST-02; for the cheapest entry to the same chip, the T6PRO.

Shipping, returns and warranty

• Shipping: Douk Audio's current shipping page says orders are generally processed no later than the next business day and arrive in 2-8 business days, with duties, taxes and customs fees included in the checkout price unless noted otherwise.
• Older shipping terms are still online: airmail at 10-25 days for parcels under 2 kg, DHL, UPS or FedEx at 5-8 days above that, and a line saying the store is not responsible for import duties. Check the delivery estimate and any duties at checkout.
• Returns: ask within 30 days of delivery and wait for approval before sending anything; an approved return has to ship within 7 days. Items need all packaging and accessories and no excessive wear, or the store can refuse them or refund part of the price. Refunds go to the original payment method after inspection.
• Not refunded: original and expedited shipping, duties, taxes and customs charges, unless the law requires it or the store made the error. The return page does not say who pays return postage, and the older refund page excludes mistaken orders and change-of-mind returns from free after-sale service.
• Warranty: 24 months from purchase for manufacturing defects, with free repair, a replacement unit and free shipping both ways for covered repairs. Drops, liquid, DIY repairs, lightning, extreme temperatures and misuse are excluded (partial fees may apply), and damage from weak packing on the way back may not be covered. The older refund page still says 1 year.
• Seller: the site is run by Shenzhen Anba Technology Co., Ltd (Shenzhen, China) and HONGKONG LONGSHENG Import and Export Trading Co., Limited (Hong Kong); support is by email at [email protected]. These terms cover orders placed on doukaudio.com; other sellers apply their own.

For this product, the page lists shipping from US, UK, EU, AU and China warehouses and shows Free Shipping, 2-8 Days Arrival, 30-Day Return and 2-Year Warranty badges near the price, plus a notice that shipping to all regions starts December 1.