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Douk Audio ST-02 HiFi Integrated Bluetooth Tube Amplifier Review

A 2.1-ready integrated amplifier combining a DAC, TPA3255 speaker amp, ECC83 tube stage and headphone amp in one chassis, with Bluetooth 5.4 and a dedicated subwoofer output. Listed as a pre-sale item.

3.73.7 out of 5 starsUpdated October 14, 2026
$199.99Price checked October 14, 2026
Check price at Douk Audio
Douk Audio ST-02 HiFi Integrated Bluetooth Tube Amplifier

Our verdict

The ST-02 is a strong value in the budget integrated-amp class: DAC, TPA3255 speaker amplification, an ECC83 tube stage and headphone outputs in one aluminum chassis for $199.99. The adjustable high-pass and 150Hz subwoofer output give it genuine 2.1 credentials, and swappable op-amps plus tone control with bypass keep it tunable. Just note it is currently a pre-sale listing, so it ships when stock arrives rather than immediately.

Best for
Budget-conscious listeners building a compact 2.1 system who want speakers, headphones and a sub driven by one do-it-all amplifier
Skip if
You need gear that ships immediately or want powered speakers — this is a pre-sale amplifier that requires passive speakers and a powered sub
Check price at Douk AudioHow we research

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 $199.99 it sits in the budget integrated-amp category, an evolution of the ST-01 PRO built around a TPA3255 amplifier chip rated for up to 300W x 2 into 4-8 ohm passive speakers. 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.

Shipping is worldwide with free and expedited options; cost varies by country. Orders under 2kg ship airmail in an estimated 10-25 days, while heavier orders go by DHL, UPS or FedEx in 5-8 days. Import duties and customs fees are the customer's responsibility. Returns are free within 30 days for a full refund, and every item carries a 1-year warranty; excluded are orders placed by mistake, man-made damage or misuse, subjective change of mind, and anything else outside the warranty terms. As this is a pre-sale listing, the amplifier ships when stock becomes available.

What we liked

  • One box covers a full system: DAC, stereo speaker amp, tube preamp stage and headphone amp, evolved from the ST-01 PRO platform
  • TPA3255 amplifier delivers up to 300W x 2 into 4-8 ohm speakers, with Post-Filter Feedback for more consistent response across loads
  • Real 2.1 integration: adjustable 20-230Hz high-pass for the mains plus a 150Hz low-pass SUB OUT for a powered subwoofer
  • ECC83 tube stage with 180V operation, large VU meters with adaptive (AGC) sensitivity, and 34 backlight colors on a TFT display
  • Four socketed NE5532 op-amps for rolling, plus 3.5mm and 4.4mm headphone jacks with headphone/speaker switching

Worth noting

  • Pre-sale item: the listing takes orders ahead of stock, so delivery is delayed compared with in-stock gear
  • No speakers or subwoofer included — you supply 4-8 ohm passive speakers and a powered subwoofer to use the 2.1 output
  • Digital and Bluetooth features depend on your sources; the description lists no streaming services or app control outside the package

Questions before you buy

Does the ST-02 include speakers or a subwoofer?

No. It is an amplifier: you pair it with 4-8 ohm passive speakers, and for 2.1 listening you add your own powered subwoofer through the 150Hz LPF SUB OUT, using the adjustable 20-230Hz high-pass to keep deep bass off the main speakers.

What sources can I connect?

Bluetooth 5.4, PC-USB, optical, coaxial and RCA inputs, plus direct lossless playback from USB drives. Headphones connect via 3.5mm or 4.4mm jacks with switchable headphone/speaker modes.

Can I upgrade the tubes or op-amps?

The description highlights a custom ECC83 tube stage and four socketed NE5532 op-amps, explicitly designed to leave room for sonic exploration on your own schedule.

What are the shipping and warranty terms?

Shipping is worldwide with free and expedited options: under 2kg by airmail (10-25 days), over 2kg by DHL/UPS/FedEx (5-8 days), with import duties paid by the customer. Returns are free within 30 days for a full refund and every item has a 1-year warranty, excluding orders by mistake, misuse, change of mind, and anything outside the warranty terms.

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