Pros: solid rich bess, smooth but detailed treble, great musical sound
Cons: none I can hear, but I haven't tried more expensive home amps
Fantastic little desktop DAC/AMP.
I'm using JH-13 Pro IEMs exclusively.
I started with an ibasso T3, which was nice. Upgraded to a RSA Shadow, since I have IEMS. Decided that since much of my listening is done at my desktop, the Shadow's price would be better spent on a DAC/Amp combo. Since I didn't want to lose the portability, and use them for IEMs, I got the iBasso D4.
If you look up that DAC/amp, it's got an incredibly solid reputation on its own. I loved it. Then I got the hiflight topkit, and switched out the op-amp to class A and left the stock buffers. This made is sound absolutely incredible. Then I purchased the special high-power 9.6v batteries you can get, which have be even more bass solidity and fullness. Just a dream. HeadphoneAddict, who's heard and compared more than I'll ever do in this life, has called this setup the equivalent of the incredible PICO standalone DAC + the top rated RSA P-51 amp. Pretty high praise. And 1/3 the price of this combo.
Well, short review of the Sparrow - it's better than the upgraded D4, and that's all I'm going to say. I decided I really only wanted to use my JH13s straight out of my iphone 3gs, since it sounded very good, and I can't be bothered to carry an additional portable amp. So it came down to a straight 1 on 1 in terms of sound quality. I ordered a Sparrow from Audio-GD having heard such great things about the FUN, but wanting a smaller unit. I asked for some changes to the stock B unit- I upgraded the volume pot to class A for $7, which everyone should do, it makes the volume track evenly straight to the bottom. Then I upgraded the stock DIR 9001 (lowest jitter - no one needs 192kHz) and the DA1852 (better highs) to class A, and finally I had them lower the gain from whatever it is original (+6?) to +3 to work with IEMS (though it's still perfectly loud for my Sennheiser 580s). I thought the optical to my powerbook would be just as good or better than the usb, so I saved $25 and went with the BNC version.
The resulting amp is nice and small on my desk, looks great, but has a fullness and richness that the D4 can't match. It feels more powerful and authoritative on the lowest register, and on the top end, it has a smoothness - while keeping all the detail - that is more musical and enjoyable than the D4. Songs that I almost couldn't bear to listen to loud because the treble was too grating are now wonderful. I think this is because of his ACSS thing.
I'm not going to make too much of the comparison - I think they both sound very similar, and you couldn't go wrong with either for the price. Ibasso makes great products. I've loved the T3 and the D4. The D4 with the add-ons was about $100 more, but it's portable - which is great for some people, esp those with large headphones that need the power. The Sparrow has a slightly fuller, richer sound, and you don't need to fuss with charging batteries, and cost less. So it was a no brainer for me.
The only thing I'd think of upgrading this to is the NuForce Icon HDP, which would be almost 3x the price. Would it be 3x the quality? I seriously doubt it. With IEMs I'm not going with a tube amp, so I think I'm pretty much set. Very, very satisfied customer. Will wait a year or two and then see what new innovations the market brings.