Sorry i think i read your post wrong. The original was usb powered, without the balanced out, the new version is ac powered with the balanced out. I thought you meant you wanted usb powered only

peti said:

As long as the original you mentioned has a balanced output I'm indeed interested...

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No problem. I'm looking for an AC powered DAC/amp with balanced output and usd input. Anyone have any impressions of this Fostex model yet?

The USB-powered model, the A4 has one upside - it is (somewhat) mobile as it can be powered off a battery pack. But it has a couple of downsides, one being quite bad - it gets fed 'dirty' power thru the USB cable which unquestionably impacts clarity (though it can be resolved by using dedicated USB signal 'washer' but it all becomes now quite expensive). Also as mentioned above, its inability to drive high impedance cans - 600 ohms are out of question altogether, 300 maybe doubtful too.
 
A4BL on the other hand, AC-powered and balanced takes care of these two problems. If only Foster implemented a truly balanced architecture in the amp, that is separate circuits for each channel, it will be exactly what the doctor ordered. And I would think they did that, otherwise there isn't anything balanced here really, we'll see... I think I am getting one either way....and modifying my TH-X00s when they come in May to balance them with 7Ns OCC cable, that should be pretty sweeeet... then finally getting some 600 ohms.... ok, so that's my plan

Yep, if it's truly balanced I will get one for sure.

Looking nice in action!
 

 
Also, found some factory info about this amp-dac here:
 
http://www.fostexinternational.com/public/images/news_img/HP-A4BL.pdf
 
Anyone knows yet if it's a truly balanced artitecture?

The specs on paper for the balanced terminals are great: load impedance - 16-600 ohm, THD - less than 0.04% at 1kHz, frequency response - 20Hz - 80kHz (+-3dB, 32 ohm 10mw), even for the unbalanced headphones output. Not bad, not bad. And in a meantime I revisited the whole balanced thing (being fascinated with it for years, but until just recently it was never within monetary grasp...well, for me at least) - so in short, a balanced connection needs truly balanced architecture between the components (DAC and the AMP here, even if only internally) in order to eliminate ground loop interference, which is the whole idea behind balanced - no humming or other unwanted noise artifacts.
 
Sooooo, when we throw in the fact that this is Fostex we talk about here and the device is physically made in Japan, plus all the glowing reviews about the A4's performance (and A8 too, I'd think A4BL must eclipse the A8 given the advance of technology and materials since the latter was conceived) - I am starting to plan for real how I will convert my cans to balanced connections, all of them, not just the TH-X00.
 
I've also been intrigued lately by going for balanced headphones in a different way, but it now seems the A4BL may be the best (and most bang-for-the-buck) way to go. Not to mention that the A4 has an opamp that when upgraded takes it to a whole new level, and my expectation is that the A4BL will share the same opamp design. Which if true, will be just unbeatable combination all around. I can't wait for someone to take a peak under the cover and break the details for us all....how long will that take....I'll stay put for now and actively plan, actively....maybe not for long, we'll see

peti said:

Looking nice in action!
Is this yours? Impressions?




Also, found some factory info about this amp-dac here:

http://www.fostexinternational.com/public/images/news_img/HP-A4BL.pdf

Anyone knows yet if it's a truly balanced artitecture?

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Is this yours? What are your impressions?

No, no. It's an image I found on the net. Should have mentioned it, my bad.

Can be the cheapest balanced dac/amp I have ever seen, bar the matrix mini-i. I hope this catch on in head-fi, so that more reviews will follow.

Dang it! Now I'm interested and I just sold my JDS Labs element, picked up a Schiit stack and I still would like to know how this turns out. I mean, I do have 15 days.

waytoocrazy said:

  Dang it! Now I'm interested and I just sold my JDS Labs element, picked up a Schiit stack and I still would like to know how this turns out. I mean, I do have 15 days.

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Yea I'm interested too. I currently own the regular A4 and I'm very happy with it, plus the design is beautiful - very intriguing that they're offering a balanced option for just an extra 50 dollars or so given how much praise balanced amps have been getting, especially considering it's even AC-powered as well rather than just USB.
 
I could easily buy balanced cables for every headphone I use because they're all detachable and all have 70 or less ohm impedance so lack of power is not a thing (it's very rare I listen to music loud either way) so I'm left wondering how this balanced dac/amp priced at 400 would fare against say 1000~ range non-balanced options such as Resonessense Concero, Audeze Deckard or the Woo WA7 for example.

Last month, i bought one from Amazon Japan; so i think i am qualified to post my own experience and impression with this wonderful little gadget:
First, let's talk about its build quality; i think it is built like a tank with all aluminum body and polished front panel; however the four screws left on the top metal cover are eyesore but according to the owners of the original model A4, their presence may faciliate the replacement of OPAMP, which i have found is not so for A4-BL; more on that later. 
Second, about its sound qualtity: i have some highly sensitive IEMs and some high and low impedance cans to pair with my A4-BL; and they pair well; the sum up, the sound of A4-BL is very neutral, resolving and spacious, not colored, more like FOSTEX adopting a reference tuning on this one, which may displease some audiophiles who have preference for a very colored sound and find the sound of A4-BL a little boring; it is noteworthy that i have only listened to the SE and have not tried the BAL OUT, which may be more powerful and euphonic judgding from the specs (300MW BAL vs 150MW SE); having read the A4 thread, i am very intrigued to try OPAMP rolling on A4-BL but my attempts to do so failed because this required the complete disasembly of the entire metiallic enclosure, taking out of the PCB and even the removal of the potentiometer, which is very tricky; however I do have a careful look at the internal PCB layout and find it quite different from that of the original A4  because FOSTEX does adopt a TRUE balanced design on this one. First I see three NJR2114Ds and two OPA2134PAs soldered onto the right corner of the PCB with a replaceable DIP version of OPA2134PA on a DIP socket, which i think is right located at the gain stage of the PCB. In addtion, what makes me think this is a truly balanced design is that channel imbalance issue frequently found on non-balanced amps is non-existent on this one. On top of that, the new type of capacictors touted by FOSTEX in its ads are actually NICHICON FG series and I do see two or three MUSES-series capacitors.
I think what i need to do now is to find a pair of balanced headphones to see how it pairs with A4-BL; i eye for BEYER T5P 2nd GEN, but boy, what a hefty price to pay! my wallet is crying.

Erjiaihaozhe, this is great news, first-hand experience at last!
 
I am very interested in the balanced out, and I'd go as far as saying 'only in the balanced out' (and anyway, standard outs on balanced gear tend to be more of an afterthought). And will be great to hear impression from pairing with headphones of higher quality, where the benefit from balanced signal would be felt most. Can't wait to hear more on that.
 
I'm also very interested in the potential for opamp rolling, in fact if it proves not possible or nearly impossible I'll likely pass on it. I truly hope this is not the case, and that a bit of soldering skills will managed to pull it off. It would be great if you can post, whenever time allows you, some pictures of the board, specifically of the OPA2134s' locations that could give us an idea of what to expect/prepare for.

[EDIT] Wrong post. Thanks Villy!
 
Well, meant to say if only this balanced amp/dac had 2.5mm balanced, so as to make it more flexible. Still, there is no dedicated amp with 2.5mm balanced, so I reckon no hope of seeing that, unless we use a cable adapter. 
 
By the way, is modding a pair of headphones to hot-swap cables difficult? I am fear that the soldering, drilling and different types of wire may cause some kind of signal interference, especially on wood cup. (I am using TH-X00, by the way).

I would think the reason Fostex made XLR4 as the only balanced out option, is that this is a stationary device and as such the expectation is that users will be plugging full size cans rather than IEMs. Well, actually the main reason is that HP-A4BL was in fact designed to specifically match with the redesigned TH-900 MK II, which now also comes with XLR4. As for modifying cans to make them balanced - I'd say go for it, it is worth 100% assuming you have a fully balanced setup. And even if you don't, say only your amp is balanced and your DAC is not, you still will notice a differences like wider sound stage and increased detail/clarity.