Integrated amplifiers — ToneWinner AD-66DPRO

The AD-66DPRO is an entry-level integrated amplifier from Tone Winner, a Guangzhou audio company. This model is the upgraded version of the AD-66D and adds an MM/MC phono input, Bluetooth 5.0 and a new mobile app to a 2.1-channel amplifier that pairs a Class A biased output stage with an internal DAC and several digital inputs.

Key specs that matter

Rated power is 100 W per channel into 8 ohms and 170 W into 4 ohms. Voltage gain is at least 39 dB, the frequency response extends from 20 Hz to 100 kHz, signal-to-noise reaches 95 dB (A-weighted) or better and THD stays at or below 0.025%. Input impedance is 20 kohm. Analogue connections comprise a single balanced input and three single-ended ones next to the MM/MC phono stage. The chassis measures 444 x 106 x 436 mm and weighs 11 kg.

Engineering and use context

In the AD-66D family, every channel uses two pairs of Toshiba TTA1943 and TTC5200 power transistors. They are biased to stay in Class A at low levels and move into Class AB only as output rises, which avoids crossover distortion at normal listening levels and runs cooler than a full Class A circuit. The input stage takes a single-ended signal and delivers a differential output, raising voltage gain while keeping noise low. Volume and tone are set by a New Japan Radio NJW1194 electronic controller in 0.5 dB steps. A custom toroidal transformer feeds a supply with ELNA and custom electrolytic capacitors of up to 15,000 uF. On the earlier AD-66D the converter is an Analog Devices AD1955 chip, and the digital inputs cover USB, optical, coaxial and HDMI ARC, with a micro SD slot and a USB port for local playback. A dedicated circuit protects the speaker outputs, while a sub out turns the amplifier into a 2.1 system. The Bluetooth 5.0 receiver handles wireless playback from phones and tablets, and the Tone Winner app selects sources and adjusts volume.

Pairing

The AD-66DPRO is meant for bookshelf speakers and moderate floorstanders in rooms of up to about 25 m2. With the phono input added in the PRO version, a turntable connects without an outboard stage, so a record player, a television and streamed music can all run through one chassis. A subwoofer completes the 2.1 setup for film and music, and Bluetooth with the app removes the need for a separate streaming box.

Alternatives

Tone Winner's AD-2PRO+ is a larger integrated amplifier with switchable Class A operation.