This is a measurement and comparison of JDS Labs USB OL DAC against the NWAVGUY's Objective DAC (also sold by JDS Labs). I also compared it to my reference budget DAC, the Topping D30. See my measurements of Objective Rev b DAC here: https://audiosciencereview.com/foru...dslabs-odac-rev-b-compared-to-fiio-e10k.2068/ And topping D30: https://audiosciencereview.com/forum/index.php?threads/topping-d30-dac-measurement-and-review.2016/ The JDS Labs OL DAC comes with USB-input variant at $99 which is what I purchased. And another with Toslink optical input pushing the price a whopping $40 more to $139. The Objective DAC sells for $129 which is the same price as Topping D30. But topping is a lot more feature rich with Toslink and S/PDIF inputs.As you see in the above picture, the OL DAC improves on the Objective DAC with the addition of linear external DC input at 15 volts.Physically the box is the typical DIY type box with a bid of texture added for good measure. There are no feat on it so it is easily dragged by its cables. It came with a monoprice labeled USB cable which I did not use.The cardboard box that it came in gets the award for the cheapest and lousiest looking packaging you can imagine. It would make an Apple designer go on hunger strike after just one look. Yes, you don't use the box but even budget $30 chinese DACs come with better packaging than this.I tested the unit using Roon as usually playing the signal files and my Audio Precision Analyzer handing the measurements. As always you see comparisons here but I got lazy this time and used my previously recorded measurements for Topping D30 and Objective2 DAC. Usually I remeasure but I think the results would be the same.I used Windows 10 inbox USB class audio driver so everything was thankfully plug-and-play. Reported formats supported are the typical under 96 Khz job:Thankfully there are no holes in there up to that limit.As always we start with our test of jitter and noise using 24-bit, 48 Khz signal (should show up as a single tone at 12 Khz). First up is comparison you have been waiting for: against the Objective Rev B DAC:It is an across the board win for the OL DAC. Lower noise floor and almost complete absence of jitter and odd spurious tone in the Objective2 DAC.The Topping D30 though, does still better:The Topping squeezes the noise floor just a bit more while outputting a bit higher level signal. So overall it is slightly superior there.Let's move to 1 Khz harmonic distortion test against the Objective DAC first:Once again we see the clear advantage in noise floor of the OL DAC over Objective DAC.On the harmonic structure, they are opposite beasts with the OL DAC generating odd harmonics and Objective, even. This translates into potentially more objectionable audible issue for OL DAC as harmonics go up. But the levels are so low that I can't make a practical case for it. Overall, I give a small victory to OL DAC here.I forgot to save the comparison against Topping D30.Looking at the past measurement, the Topping D30 has the same harmonic structure as the Objective DAC and at lower levels. So the Topping D30 wins this round again.Lastly I tested the "linearity" of OL DAC while trying to reproduce a very low level sine wave, comparing it to Objective DAC:The lower noise of JDS OL DAC makes a small improvement her as we go from negative to positive swings but the difference is very small. Both are pretty respectable for this price range. Topping D30 is also within the same ballpark.From engineering point of view, JDS Labs and their design shop (same one as Objective DAC) have done a nice job of improving this DAC. At $99 with the same feature set, I really see no reason to purchase the NWAVGUY's Objective Rev B DAC. This is cheaper and better.Compared to the Topping D30, it loses out on measurements and features. Addition of Toslink makes it even more expensive than Topping D30 yet still lacks S/PDIF. Topping also supports 192 Khz and DSD format which the OL DAC does not.If you like this review, please consider donating funds for these types of hardware purchase using Patreon ( https://www.patreon.com/audiosciencereview ), or upgrading your membership here though Paypal ( https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).