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iBasso D2 Boa Headphone Amplifier - iBasso D2 Boa Headphone Amplifier

By Stuart Andrews



  • Recommended by TR
iBasso D2 Boa Headphone Amplifier


Our Score:


As you might expect, much also depends on the headphones. With a pair of Grado SR60s, you gain some benefits in terms of a bigger sound and added presence, but probably not enough to make the expense worthwhile. Switch up to the Grado SR125s, however, and there's a more noticeable impact; even though these are still sensitive, 32Ω cans, you can appreciate the extra warmth, detail and general ‘zing' that you get with the D2 over the stock amplification.

I found an even more impressive boost with a pair of AKG K141 studio headphones. Rated at 55Ω, they're a little harder to drive than the Grados and can, with poor amplification, sound thin. I like them a lot for classical music and - rather oddly - vintage rock, but they're not the most versatile set of ‘phones I have to hand. With the D2, however, they take on a new lease of life. I don't think the D2 colours the sound or boosts the bass in the way that the FiiO E5 does, but there's a new richness of tone in the bass and mid-range with it attached, while clarity - already a strong point of the K141s - is, if anything, enhanced.

However, the D2 also gives you another way to get a little more from your iPod. You see, the iPod's dock connector actually provides a line-out signal, and with the correct cable or adaptor attached, you can take this directly into the D2's input, bypassing the iPod's amplifiers altogether. The result was something of a revelation to me.

I've listened to Massive Attack's Teardrop hundreds of times through the iPod through a bewildering variety of headphones, but I'd never heard it sound this good through the Apple player, the huge bass underpinning layers of detail in the vocals, sounds and samples that I normally struggle to resolve. It's an odd thing. I would plug in the AKGs or Grados directly into the iPod and think "Actually, that's not bad. Maybe I'm imagining the difference." I'd then hook up the D2, play the same tracks and think "Blimey - that's what I've been missing."

The fact is, once you've got used to listening to a decent pair of headphones through the D2, it's very hard to go back. Tracks that used to sound OK suddenly sound thinner, less exuberant and less detailed.

The same holds true when you use the D2 as a combination DAC/Amplifier with a PC or notebook. The difference between the output direct from the headphone socket of my HP laptop and the output of the D2 was a lot larger than I'd anticipated. I'd listen to, for example, the opening strings and weird electronic noises on Joga from Bjork's Homogenic and think they sounded okay. Then I'd plug in the D2 and marvel at the new levels of detail, and the way in which the dynamics of the track grow in complexity and life.

The opening bass line of The Smashing Pumpkins' Ava Adore used to sound perfectly good through the bare headphones output, but having listened to it with the D2 hooked in, it now sounds cluttered and dull. With the Bill Evans Trio's take on Some Day My Prince will Come from Portrait in Jazz, there's a new lightness and spring in the sound that I hadn't heard through the Grados before - or at least not to the same extent.


April 23, 2009, 3:54 am

Thanks for the informative review Stuart - I am really tempted, but was wondering if you had a chance to listen to an ipod hooked up to this through a pair of Shure SE530s?


April 23, 2009, 2:53 pm

I'm afraid I haven't. Generally speaking, I found the improvement in sound with in-ear models to be less spectacular than with full-sized cans - partly because the in-ear 'phones tend (as a rule) to be easy to drive. I'm sure you'd find some difference, but whether it's 𧵝 worth of difference is another matter.

For anyone else out there, I've just been listening to the iBasso with the iPod and a pair of Sennheiser HD595s and the results are extremely impressive. Superb clarity, positioning and definition, as you'd expect from the Sennheisers, but now with a little added welly.

Shaun @ HiFi Headphones)

April 23, 2009, 3:29 pm

We've had some very enthusiastic comments from customers using amps like the iBasso D2 to drive IEMs.

In my experience it's worthwhile with high end in-ear earphones (like the SE530) if you feed the D2 from the Line Out Dock (30 pin connector on the bottom of the iPod). It's particularly effective with higher impedance models like the Klipsch X10 or Sleek Audio SA6.


April 23, 2009, 3:50 pm

To echo Shaun, I've always found the iPod/iPhones particularly poor at driving dual/triple/quad driver phones as they generally require more power (simple logic, no?). so a headphone amp - especially amplifying the line-out not the headphone jack - would be worthwhile.

I'm definitely tempted to get one of these for my desk at work - lossless audio files through a decent DAC will make me very happy!


April 23, 2009, 4:14 pm

As I type I'm listening to my iPod from its line-out, through a CMoy amp and into a pair of SE530s. I can confirm that the amp lends the audio a far more powerful sound, warmer in tone but far superior to what I get from the headphone jack - particularly at higher volume. My amp's actually a Penguin Royal, as featured in TR's 'Fire in the Head' article.


April 23, 2009, 7:00 pm

Shaun and Hugo are right on those points, and it's definitely worth experimenting if you have some high-end IEMs - particularly high impedance models. I didn't have any that were that expensive or that refined to hand during testing (by preference, I tend to use over-the-ear 'phones myself).

As I said in the review, the results I had with full-sized phones and the line-out on an iPod Touch were actually quite amazing, and I'm still listening to FLAC and Apple Lossless files through the iBasso from my PC nearly a week after writing the review (usually when I should actually be doing other things). If you have the cash, it comes highly recommended.

Carl Abudephane

April 23, 2009, 7:10 pm

To use the line-out 30 pin connector from the i-pod, what sort of cable would one require in order to get the best results?


April 23, 2009, 7:31 pm

@Carl: Depends how much you want to spend. A simple 3.5mm stereo cable from any of the myriad iPod docks will do the trick. At the other end you can spend $200 on an ALO Cryo cable. There's a lot of conflicting opinion on how much difference the extra money makes.

Here's the iBasso adapter: http://www.ibasso.com/en/pr... You can get these for around 㾸 with some Googling.


April 23, 2009, 7:33 pm

I've had my d2 for about a 6 months now and have loved every minute of, especially paired with my Grado's.

I have a pair of Phonak PFE's which have a relatively low impedance rating and they are almost brought alive when using with my 5g rockboxed ipod, heaven.

For LOD's you can;t go far wrong here http://www.aloaudio.com/sto... and here http://www.qables.com/shop/...


May 27, 2009, 3:49 am

Comedian - Wich Grado's have you been using with the d2?

This amp looks very atractive. Im on my way to order some Grado SR80 and I have been thinking about getting a nice amp to get a good sound, it's just that I have been suffering because some say that they don't need to be amplified at all. I also have consider the Total Bithead amp from the guys from Headroom but it seems that the Ibasso is a better one.


May 29, 2009, 3:10 pm

Ive measured it's performance based on the USB DAC. It is important to notice that the first analog stage after the dac clips with 0dBFS in, it's unclipped with -3dBFS in (or below).

In plain words - you need to set the volume in your playback application to maximally 71%, ie the volume in media player or winamp. Else it will clip.

Maximal not-too-distorted output (if you plan driving a poweramp or active speakers with it) is 1.2Vrms


October 29, 2009, 2:54 pm

The real question is whether the Lithium Ion battery is replaceable. Otherwise the whole thing is useless in a couple of years. There is a monstrous conspiracy of silence regarding this nowadays.


May 7, 2012, 2:30 pm

I like the monster headphones, the sound headphones price what kind?

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