Pros: Crams a lot of features in for the price: DSD, DXD, volume control, LED indicator of sampling rate, RCA output
Cons: Ultimately, the sound quality is substandard
I had high expectations of this based on so-called "professional reviews" listed on the iFi website & ones here. Particularly the one from the audiostream "Greatest bits" award: http://www.audiostream.com/content/ifi-nano-idsd-dacheadphone-amp. First listening impressions were not great. I let it run for a few days to be sure, tried the different filter settings, tried the line out vs the headphone out, tried different sampling rates. All to no avail.
In Standard mode, contrary to what the manufacturer states, Standard Filter sounds better because the music has better pace, rythm and timing (PRAT).
Overall though, it sounded somewhat off.
So I measured it... results were not very good. The ODAC easily outperformed it in 44k & 96k. The ODAC can't do higher sampling rates than that so no comparison there.
Vs the ODAC - you get a fancy box, nice short USB cable, RCA stereo leads, 2x straps and a rubbery protector to place between devices, DSD, DXD, >96kHz PCM, Sampling Rate indicator and internal battery. It is also better presented with a commercial appearance. But, after a few days, that doesn't matter anymore. The ODAC is simply better sounding for 95% of the music you throw at it. I'm not sure if I'll keep the iFi just for the higher sampling rates & DSD (which I have compiled quite a bit of).
I tested this from a laptop, a PC, and a Samsung S3 using USB Audio Player Pro. Measurements were with RMAA 6.4 using an E-MU 0204 USB Audio Interface using ASIO drivers with identical loads (my custom amp / Audeze LCD-2) on another PC - ie. One PC or phone playing the test signal through the devices, and one PC recording via the E-MU.
The only change in the tests were the DAC, then levels were matched. So it is a direct comparison.
Click here to view the test results!
The four big failings are: Frequency response, IMD, THD, and a noisy volume control.
PS- I did further measurements with a laptop as the source, running 96kHz/24-bit. Comparatively, the iFi was similarly worse measuring pretty much across the board
ADDITIONAL MEASUREMENTS FOR THE SKEPTICS: https://dl.dropboxusercontent.com/u/90236454/iFi%20iDSD%20Nano%20vs%20ODAC.pdf