Epiphany Acoustics EHP-O2

General Information

EHP-O2 Portable Headphone Amplifier

The EHP-O2 is a battery powered, portable headphone amplifier. The electronics have been designed by blogger NwAvGuy. The amplifier measures superlatively and they speak for themselves when describing the quality of the amplifier. This has been achieved by very careful component selection, taking advantage of their specific performance characteristics as well as shrewd electronic engineering.

It comes equipped with 2 rechargeable NiMh batteries for portable use as well as an AC adaptor for desktop use and charging purposes.

A built in gain switch allows the user to choose the appropriate gain for the source and headphones/earphones being used.

The EHP-O2 has:

1 x 3.5mm input jack
1 x 3.5mm output jack
1 x power inlet
1 x gain switch

The electronics in the EHP-O2 were designed to offer superior performance in every key specification possible. A snapshot of the measurements are:

THD @ 1kHz: 0.0017%
Noise level (ref 400mV): -105dB
IMD: 0.001%
Power output @ 33Ω : 641mW
Crosstalk: 65dB
Channel balance 0.6dB
Battery life: 8 hours

The EHP-O2 portable headphone amplifier is hand built in the UK.

DIY Builders: Unassembled PCBs are available for DIYers to build the EHP-O2 themselves.

Latest reviews

Pros: Sound stage, clarity, build quality.
Cons: Nothing
Where do I start? Everyone who likes audio reproduction has heard of the Objective 2. Epiphany Acoustics has done a great job of building this amp and I'm a very happy owner!
Pros: Low noise floor, high value and solid build quality
Cons: Gain even on 1x mode is too high for some sensitive IEMs, input 3.5mm jack is in the front (bad ergonomics)
This is a traditional Benchmark DAC-1 style "wire with gain" sound for a very low price. Not the last word in emotional expression, but the O2 has a very silent inky background and good clarity. 
For people new to Head-Fi, you can now get an amazing budget rig by getting this and the EDAC. Pair them with good mid-range headphones like the Sennheiser HD 600/650 and you have a fantastic beginners setup. For those who don´t want to make headphone audio a more serious hobby it´ll even be a good "buy, use and forget about Head-Fi.org" setup.
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Pros: audio & build quality
Cons: Portability & battery life?
Over a period of time I bought a FiiO E5, a CMoy and a FiiO E11, which all raised the soundbar. I bought the O2 because of NwAvGuy's writing.
The amp turned up one and a half month late and initially without an AC-AC power supply. But thanks to good communication with Epiphany's Oliver this was not such a very big deal.
The O2 drives my Audio-Technica ATH-M50 easily. My iPod touch V4 32GB is connected to the O2 with a simple FiiO line out dock L9 connector. Expensive cables are no longer necessary, I assume because of the high input impedance of the O2. I have attached the iPod to the O2 with 2 pieces of sticky double sided foam tape. I have put an old belt on an old leather bag to carry the two.
You notice immediately that the O2 is totally silent when music is not played.But when it plays... I have never heard bass, mid range, treble, sound stage and instrument separation of this quality.
Thanx NwAvGuy and Epiphany!!!
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The O2 is also an excellent walking-the-dog and biking amp!
Thats one sexy looking set-up
My wife thinks I look like a fool, but I don't mind.


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