[Review] Fostex HP-A4 DAC Headphone Amp [Review]

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Fostex HP-A4 DAC Headphone Amplifier Review

Well well well, what do we have here then.. the Fostex HP-A4 DAC & Headphone Amplifier :)

I did promise a review long ago, so apologies to that person who's hopefully still around.. can't remember their username unfortunately :p

So this unit supports the usual PCM audio up to 24bit/192kHz and DSD audio up to 5.6MHz playback.

For those interested in the headphone stage:

Phones Connector: Stereo phone
Max Output: 100mW (32-ohm loaded)
THD: less than 0.04% at 1kHz, 32-ohm loaded, 100mW
Frequency response: 20Hz - 80kHz +/-3dB (1kHz, 32ohm loaded, 100mW, FS 192kHz)

The Fostex HP-A4 uses the Burr-Brown PCM1792ADAC chip and OPA2134 op-amp. It's worth noting that you can "roll" (replace) the op-amp which is very easily accessed by just unscrewing the top of the unit.

It is a compact unit with dimensions of 113mm(W) x 34mm(H) x 155mm(D).

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Full specs can be found at: http://www.fostexinternational.com/docs/products/HP-A4.shtml

So apart from the recycled packaging and unit itself, you are presented with 4x rubber feet and a relatively short USB cable.

I'm sure some people might prefer using their own cable anyway ;)

Anyway the unit itself delivers a great presentation with aluminium sides and a gloss front. One minor gripe I found is the ports at the back are slightly slanted.

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Solid and weighted feel to the volume knob, buttons are on the light side but a non-issue really.

The input button as you would have guessed allows you to switch the input between optical and USB.

Filter allows you to change between two settings for cut-off/roll-off, which vary depending on format of audio. Haven't really needed to use this but might come in handy for someone.

Gain button adds 10db of attenuation which is a nice little boost that'll come in handy for some headphones.

Moving from the front panel of controls, at the back we have 2x RCA out, optical in/out, Micro SD for firmware updates and a USB connection.

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Sound
Moving onto the nitty gritty, or the opposite in this case..

First I'll be using the mighty Sennheiser HD 598 headphones to test which don't take much to drive. So what we hear is great mids that are very clear and detailed, bass isn't overpowering at all and what you would describe as smooth but this might be describing more of the headphone profile. Highs are well presented without being harsh at all.

Most of these characteristics are a testament to the DAC for its flat frequency response that brings about crystal clear clarity. So the rest is really up to you ;) Obviously it should make factors like sound separation and sound stage a piece of cake too.

One thing probably worth noting is that the headphone amp might struggle with high impedance headphones, unfortunately I don't have any to test with.

Comparison
For a comparison with another DAC I'll be using my MSI MPOWER Z77 motherboard which utilises the Realtek ALC 892 codec.

So the bass on this definitely hits harder, with more apparent boom and punch in kick drums for example. I prefer this but then again I'm a bass head so it's down to your taste of music ;) Also you'll have to forgive me that the HD 598s are my first pair of "proper" headphones, as generally I stick to desktop speakers.

Anyway it is apparent that the vocals are definitely more crisper with the Fostex unit. Clarity and depth is also ahead(pun intended?), this could just be placebo but I don't doubt this unit at this price.

There's not much in it between the highs as far as I can tell, then again I'm no expert. You'll have to forgive me for the lack of audiophile jargon, hopefully I've done this unit justice!

Don't get me wrong though, these days modern motherboards are more than capable and will be adequate for most users.

Testing with speakers
Time to throw the Adam F5 studio monitors into the mix..

With the HP-A4 there is definitely a wider sound stage/better sound separation, as when you are throwing multiple instruments and clashes in you can distinguish between all the elements and listen in awe. Whereas with the motherboard it can be like, hmm this is sounding a bit messy.

Motherboard sounds warmer, which is understandable as the HP-A4 is meant to be as neutral as possible making for accurate listening.

Sound Conclusion
No bloated bass, precise as it should be. Mids crisp and clear. Highs again have a nice snap which is more apparent than motherboard DAC.

Conclusion
I hope you've enjoyed reading this, and that it can be of use to someone.

I can say that this device does exactly what it is intended to do, which is bring out the characteristcs of the output device. Of course this does mean you will have to be careful with pairing, as like-for-like might not have you dancing up and down but maybe neutral is what you're after :)

If you are after something with more sparkle for example then maybe a tube amp might be better suited. This device does however provide customisabiltiy with the OP-Amp which I believe can slightly alter the sound i.e add colouration.

So the Fostex HP-A4 is a DAC/Amp that should be suitable for most folk, as it will integrate seamlessly with your speakers/headphones :)


If you have any questions don't hesitate to ask :)
 
Nice writeup, I was actually looking at getting one of these until I discovered that it can only output 20mw @300 ohms, which is about 1/3 of what's needed for driving my HD650s properly.
 
Thanks

It doesn't seem to be a popular unit but that's not a bad thing, luckily I don't use headphones much and the ones I do are low impedance.

So people planning on buying will have to be wary of what headphones they have or plan on buying :)
 
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