

​

This is a concurrent review of two DACs, the famous "O2 DAC" by Nwavguy from our neck of the woods and the E10K Olympus 2 from Fiio. They both use the TI PCM5102 DAC chip so makes for an interesting comparison.Retail price for the JDSLabs version of the O2 DAC is $149 through Amazon: https://www.amazon.com/JDSLABS-ODAC...?srs=7812820011&ie=UTF8&qid=1510959113&sr=8-4 The Fiio E10k Olympus 2 is half the price at $73: https://www.amazon.com/FiiO-E10K-Headphone-Amplifier-Black/dp/B00LP3AMC2 While the ODAC is quite sparse package with just a USB connector and 3.5mm output, the Fiio E10 has a headphone amplifier with both bass boost and gain settings, plus a S/PDIF coax output. They are both quite small and fit in your hand so are great portable solutions to take on the road if needed.Construction quality on the outside is good and a small step above cheezy DIY packages from other companies.I simply plugged in both units and Windows 10 Creator's Edition on my laptop nicely recognized both and created the WASAPI end point which I used in Roon in exclusive mode. Roon Reported the correct sample rates for ODAC which was 44.1, 48, 88.2, and 96Khz.Oddly, the Fiio E10K only advertises 44.1, 48 and 96 KHz, missing 88.2 KHz! Not sure why it doesn't show that sample rate as I am confident the built-in DAC chip supports it. Could be a firmware bug in which case, Fiio should address.Both units worked reliably inside Roon which was nice. They did not require any of the hacks to make them operational such as not using event driven mode in WASAPI that some DACs require.Let's dive right in with our J-test signal to see levels of noise and spurious signals around our main tone of 12 Khz:For reference, I am also showing the Topping D30 (in yellow) which is my currently recommended low-cost DAC. The Topping D30 retails for $120 including shipping ( https://smile.amazon.com/dp/B01L1SD...t1_sce0_prc0_aapi0&ref=bit_scomp_smile_ddt_t1 ) and so is cheaper than the ODAC. It also has more features in the form of proper RCA jacks, S/PDIF input, external power supply, etc.As we see here, the Topping has lower noise floor and what jitter it has, is hugging the main tone so is quite inaudible.The Fiio E10 has higher noise floor and fair bit of spikes around the main tone but at higher levels than topping and more of them. But again, not an audible concern but objectively worse.I was surprised by the poor showing of the ODAC here where it also had close-in noise but also spurious idle tones above and below as the green arrows show. One pair is jutter the other, some oscillator running at the frequency that is bleeding into the output of the DAC. For a DAC that is supposed to be objectively good, this DAC sadly is not.To its credit, the JDSLabs ODAC has a bit higher output than the Fiio which is always good.Next, let's check levels of harmonic distortion using a 1 Khz tone:Again, our Topping D30 pulls way ahead with higher output (due to its use of external power supply) and lower harmonic distortions than both of the other DACs.At the other extreme, the Fiio 10 Khz has harmonic distortion that keeps going and going! Now these are at very low levels but why???The ODAC finishes in the middle of the pack. It has good 5 to 10 db higher noise floor than the Topping D30 but overall it is cleaner than E10K has harmonic order increases.For low level linearity test, we use a -90 db sine wave at 24 bits/44.1 Khz:What we are looking for is a clean sine wave. The Topping D30 and ODAC are very close to each other. The Fiio E10K however, has lower output which makes it more susceptible to noise pollution and more up and down jumps so definitely less cleaner than the other two.I did not have time to do a listening test through the line out from these two DACs. Instead, I tested them with different headphones direct from their output. In the case of Fiio E10K, I used its front headphone output rather than the rear line out.Here, the Fiio E10K pulled way ahead. It is able to get at least twice as loud as the ODAC, able to drive even my difficult load of Sennheiser HD650. Its output never gets distorted by the volume control levels out at 70-80% of its maximum setting. Turning it up further seemed to do nothing. At max volume, the output was loud enough but not uncomfortable. In that regard, more power could be had.In comparison the ODAC was rather anemic. Yes, you could listen to it but just not at loud enough levels.The winner here is clearly the Fiio E10K.From pure objective point of view, the winner here is the Topping D30. It is cheaper than the ODAC, has far better feature set including support for such things as DSD. In that regard, I can't recommend the ODAC. Maybe at the time Nwavguy thought of it, it was good but time has past and newer entrants even from budget sources easily outperform it.Likewise, the Fiio E10K easily outpaces the JDSLabs ODAC because of its inclusion of headphone amplifier. It is also half the price. So another rIf you need a little DAC and headphone for very little money, the Fiio E10K Olympus 2 is my current choice.