PerformanceThe nano iDSD LE sounds great straight out of the box. In order to get it to work, you need to install the iFi USB driver, which is available from their website. After that, you just plug in the device and it is instantly recognized. Like with previous DAC/Amp reviews, we turned all Windows "enhancements" off.
We started off by hooking it up to our HiFiMAN Edition S headphones, which it drove perfectly with volume to spare. At around 40%, you get more than enough volume to power the Edition S headphones, which are reasonably effective. The gain of the nano iDSD LE is a bit lower than that of the JDSLabs C5D at low gain. The gain setting of the nano iDSD LE is well suited to anything from efficient over-ear designs all the way down to super sensitive in-ears, which is due to its very low noise floor that is on par with that of the JDSLabs C5D. Both will present a totally black background on normal headphones. On the most efficient in-ears, like, for instance, the new Brainwavz B200s, you could hear a little static with no music playing and the volume cranked all the way up. Volume imbalance is noticeable in the first 1/8th of the knob's range. The channel imbalance disappears once you are in the usable range.
If you hook the HiFiMAN HE-1000 V2s up to it, it still plays pretty loud without distortion, but you need to push the volume knob to its very maximum in order to get enough volume for high quality masterings with good dynamics. The Edition X headphones are slightly more efficient and therefore a better match for the nano, but I would still prefer to have more volume overhead. You really miss the gain switch of the C5D when you change over to the nano.
In terms of bass, the nano is on par with the C5D, which is to be expected as both exhibit sub 1 ohm output impedance. Output impedance is important when it comes to driving low-impedance loads, such as in-ears and some semi in-ears. This coupled with the low noise floor makes the nano iDSD LE an interesting amplifier for anyone with a high-end set of in-ears. With a set of Sennheiser IE-800s, the nano is right at home, and its transparent nature and low noise floor make it a good pairing.
Detail-wise, the nano has the edge over the C5D, which sounds less natural in the high frequencies. High hats sound more natural, and the nano seems to bring forth a more airy presentation of the highs, which probably also adds slightly more space to the soundstage, which is pretty spectacular as the C5D is more expensive and highly regarded.
The differences are minor, but overall, I find the nano more pleasant to listen to for extended periods. This holds true for all efficient headphones as once you are in Edition X or Sennheiser HD650 territory, the nano misses out in terms of gain.