Very nice for the money. (and overall)

A Review On: Epiphany Acoustics EHP-O2

Epiphany Acoustics EHP-O2

Rated # 10 in Portable Amps
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Review Details:
Audio Quality
Purchased on:
Price paid: $180.00
Posted · 17642 Views · 29 Comments

Pros: Clear sound across the FR, portable(ish - size but battery), drives both IEMs and full size can well. Low noise floor

Cons: you may want RCA-ins when you get it(I did).but portable :D ! Australian wall wart, 2RCA-3.5mm plug and 3.5mm to 3.5mm short interconnects would be g

Pre-Ordered from Oliver (EA) in Oct(?). Received the unit about 2w ago.

The bad
The volume pot tracking is not very smooth (catches a bit on some positions (tactile feel, not audibly)). (will check whether pot knob gets caught on the case) (edit: yep, that's it, no real quality issue there)

To my surprise, the unit does not come with a 2RCA->3.5mm or 3.5mm to 3.5mm .I only had a fairly long and rigid one. I wish Oliver would include at least some cheap interconnects biggrin.gif

I'd probably also like a small manual explaining what not to do. (e.g. will it explode if I leave it plugged in for a weekend at work, and come back on mon to find my building charred. Or does the charging circuit cut off at a certain voltage? does it get powered from AC or via batter when AC is plugged in?), or is pressing the gain button while the unit is on bad or not, etc. How to change the NIMH batteries or something. (and rules of when to charge them for longer life or something. What warranty do we get? What are the return conditions for the warranty claims (who pays shipping where), etc)

I also wish Oliver could source Australian wall warts, but he couldn't at the time. The AC-AC 15v 0.5A adapter with the UK plug is huge. I could only find replacements w the AU plug at Jaycar and Mwave, and they're $30+ shipping ($50...). To be fair, he did give me an option of a small partial refund and me finding my own PSU, but it's probably best to just use the UK one with a socket adapter biggrin.gif

The good
That aside, I've been playing with it for a week now, and the sound is great.
Crips,extended bass and highs, present mids, great perceived soundstage and dynamics.
The low output impedance and the decent max output let me drive my GMP 450 PRO (300ohm, no idea what sensitivity. Sound great at hi-gain/about 3/5 of the vol) and UM Mage (demo)/Shure se425.

Both the IEMs and full size cans sound a lot better than my Musiland MD11 and MD30 - much lower noise floor and perceived sound clarity, fr linearity and bass quality (tales of folksy better extension and depth biggrin.gif go here). I did expect that for the IEMs, since the hp jack on MD11 and 30 is 2-3ohms, but certainly didn't expect that much of a difference for GMP450 PRO. I'm also rather surprised, just how much of a difference a low impedance output makes for IEMs.

For IEMs, O2 also sounds noticeably better than my Cowon d2 portable. (hmph, I might have to start carrying it around biggrin.gif )

The build/case all look and feel very sturdy.

Despite the designer's comparisons to Benchmark DAC, I did not find the sound to be similar (I thought DAC1 was awfully bright, almost serrating, which was not the case with the O2). edit: there is a slight qualification to this, MD11 has slightly rolled off HF as per the RMMA, so YMMV on this a bit, but I don't expect it to become awfully bright on straight (+-0.1db) FR sources.

I wish I bought a desktop version (6.5mm out, 2RCA in) and a portable version biggrin.gif, but Oliver/EA and NwAvGuy did very well.

PS I will be cracking it open next week at home and maybe posting some pics on what's inside (part quality and all, not that NwAvGuy approves biggrin.gif ), tho I'm not sure if there's any point, since the O2 thread probably has some


Talked to Oliver, he suggested the pot knob may be catching on the the case (probs is) and said they might write a manual for future versions/offer interconnects at a small fee in the future.

He also said:
" (for your reference, they are sturdy little things so there will be no issues with
> flicking between gains and the power management system allows the amp to be
> left 'on charge' indefinitely)."
Also found the warranty info on the site: (2y, EA pay for return shipping, which is very nice).
Many thanks for the in depth and balanced review. I will be taking all of your points on board to continually improve the whole product and experience :)
Thank you for the prompt replies Oliver! It's good to see the amps hit the market in a timely manner, and people can get great sounding and measuring amps at reasonable prices

I'll adjust the quality rating as soon as I move the vol pot a bit further out on Mon, and make sure less thick/rigid interconnects don't cause distortion and ringing on the output.

It's a great little amp . I might even start carrying it around w my Cowon D2, since I like the resulting sound a bit more from the D2->O2 .
Wonder where I can get relatively short 3.5mm angled to 3.5mm angled interconnects...

Might buy some neutrik 3.5mm plugs and mic wire or something from the local electronics store
ps >I'll adjust the quality rating as soon as I move the vol pot a bit further out on Mon, and make sure less thick/rigid interconnects don't cause distortion and ringing on the output.

The exact problem I'm having is the interconnect is very rigid, so it pushes to the side and the jack seems to lose a bit of electrical contact, so there's distortion and ringing/buzzing unless I place it a certain way . I'm pretty sure it's a problem on my side...
PS when I get my SM3x8 back and get the TP50RP (smeggy), I'll update the impressions
Nice realistic review.
Hey how is your SE425 versus Mage out of the o2, is the Mage twice as good?
Will eventually post a mage review (the demo pair is great on the O2 and Cowon D2). I think I've already reviewed 425. I'm not a big fan of the shure it sound it turns out. Will check if the 425 do better on O2 vs MD11/30 and D2 at work on mon (chances are they will).
Great review! FYI, the 12V AC powerpacks from Jaycar and Altronics have been tested to work with the O2. They're both <$20. Personally, I used a 15V AC powerpack from Altronics, but had to solder my own connector.
thanks for that. what's the reason it's supplied w a 15v adaptor anyway? 12v and lower amps (I could only find 15v ac-ac in 1.5a), ac-ac cost a lot less,but idk if the amp would perform to spec incl max output? (or is this for faster charging or something?)
If you feel that the Jaycar ones are ripoffs you could take a look at element14 store for the multicomp 15v, 500ma EU adaptors.( for APAC)
BTW there is a reason why you should use 15V adaptors, its because the 12v adaptors will let AC ripple through(its documented). This could result in high distortion issues when paired with low impedance headphones/IEMs. So guys, just don't compromise those few dollars on power supply.
The specs call for AC input between 14-20V, but a few people reported that the 12V AC wallwarts were pumping out around 14V AC and had no problems with those? I know my 15V AC actually pumps out around 17.8V AC?
@zeffa, thanks, errr, 17.8V under load, or when you just measure the cold running wall wart? (I presume most AC wall warts are not regulated?)

@firev1 - I see, thanks. errr, that's sorta more expensive than jaycar?

@Oliver, tried the new 2rca - 3.5mm - good contact and no noise. As suspected, there was something wrong with the cable before. Forgot the hex keys, will try tomorrow.
17.8V AC with no load (well under the recommended 22.5V max). My understanding is that an AC wallwart is basically just a transformer in a plastic shell - I don't think there's any other circuitry involved. The O2's power circuit filters and regulates the AC into +/- 12V DC.
Strange that it isn't available in your region my region seems to have it listed (though stocks are in the uk). Anyways that link was a 15W supply which is WAY overpowered.
wow, it's cheaper too.

Btw, the supplied pot outputs 19.8V AC (RMS).

M, I thought AC are very much mostly unregulated and is indeed more or less a step down transformer (I've seen some mains voltage regulators that switch transformer taps at high speed (funnily enough not fast enough according to the spec figures ), but that's certainly not it and doesn't really need it, if the amp circuit converts to 12V dc fine).

I'd relaxed the vol pot today, so it doesn't catch on the case anymore, so there are no quality issues with the amp. I've adjusted the Q rating from 4 to 5, although for the price it's a decent 5.
A finally qualification is about the DAC choice on the upstream and similarity to DAC1:
MD11 has slightly rolled off HF as per the RMMA, so YMMV on this a bit, but I don't expect it to become awfully bright on straight (+-0.1db) FR sources.
I'd say it's a quality issue with the amp if it catches on the case - and also suggest that the 3.5mm input instead of 2 RCA and 3.5mm output instead of 6.5mm seems - even if it is meant to be a 'portable amp', a silly idea. I guess it's cheaper to get a 3.5mm jack you can't see the internals of than a nice gold platers 2xRCA jack connector.
still, for the money :)