The JDSLabs O2+ODAC is just a superb combination. Good craftsmanship and performance comes together nicely in this design. The performance experience with this combination is just mind blowing. A few years back, you would have had to pay four times as much to get close to this level of performance in a small solution, and it still outperforms much more expensive amplifiers like the ASUS Xonar Essence One on core performance parameters. It does not have all the extra connectivity of the more expensive units, but it has what most needs.
The JDSLabs O2+ODAC is nearly the perfect desktop DAC/Amp. It is relatively cheap, small, and performs very well. We are really nitpicky here but the faceplate design and layout is somewhat compromised by the fact that NwAvGuy's design was very budget focused, which is why everything was pushed to the front plate to keep milling complexity at a minimum. It makes good sense on the portable O2, but it makes less sense for the O2+ODAC combination, since you will probably have the power plugged in.

Let there be no doubt that this is a world-class desktop amplifier. It drives everything from in-ears to fully sized and hard-to-power headphones extremely well, and the DAC part of the design is equally competent, since it delivers a superb headphone listening experience.