HiFiMan continues to create great sounding, affordably priced components for headphone aficionados. The company's EF5 headphone amplifier is the successor to the well-regarded EF1, and it fully lives up to expectations. The EF5 uses a two-chassis design that houses the power supply in a separate box to keep noise at a minimum. And we're not talking about a skimpy little 'wall-wart' AC adaptor, either. The DY-1 is a serious power supply designed specifically for the EF5 and includes a large toroidal transformer. Just like the EF5, it is completely hand built. But a dedicated power supply isn't the only thing that the EF5 has up its sleeve. It boasts high quality parts throughout its construction, but the most obvious detail to the build is the protruding RCA 12AU7 vacuum tube, which contributes to this little jewel's warm and lifelike sound. The 12AU7 produces voltage gain as a cascode amplifier in the first stage. The amplification stage is hybrid, though, combining the 12AU7 with a discrete component buffer stage. "The idea is to combine the sweetness of valves with the grip that they so often lack," notes England's What Hi-fi? magazine. The output stage uses an OPA275 opamp, and tweakers will enjoy trying different opamps and tubes to alter the sound quality. But we're not saying that you'd want to! The EF5 works beautifully with a wide range of headphones and excels with HiFiMan's HE5LE 'phone. This powerful amp will provide a full two watts per channel into a load of 32 ohms. The EF5 includes one pair of RCA inputs on the back panel and one headphone jack on the front panel. A high/low gain slider switch in front of the 12AU7 can be changed with a screwdriver to suit your headphones. Both the EF5 and DY-1 have an aluminum-extruded chassis.
Hand-built headphone amplifier
Separate-chassis DY-1 power supply with toroidal transformer
Tube: RCA Clear top 12AU7
Input: one RCA
Detachable IEC power cord