This is an evaluation of a Zhaolu DAC as modified and sold under the label Oritek Audio by a fellow named Ori Mizrahi. It is on kind loan from a member. I think it came out back in 2005 or so. He tells me that the DAC itself was US $250 but with Oritek mods, price went up to US $899.Given how old this unit is,I suspect it is not an interesting product to look at by itself. Modding audio products though is something people do and I thought it would be good to dig into this one and see where they have gone with it.This is definitely a budget looking DAC:The interesting bits are on the inside:Isn't the contrast amazing? The parts that came from Zhaolu are all professionally done down to little details like heatshrink around power switch to keep shock hazard low. Twisted power cables, nice and clean PCBs with lots of heatsink area and mass to keep things cool.Then we see the hack job in front that is masquerading as a headphone amplifier. There is a hole in front for headphone jack but then he runs wires to the back of the unit for a jack there???Then there is that other budget hand made PCB that I suspect is the DAC output buffer.Let's put this on the bench and see if there are any merits to these changes.I ran my usual dashboard on the unit with the volume control set to max and got this:What a horror picture show! The positive half of the sine wave is running out of steam and becoming compressed somehow. Distortion naturally shoots sky high giving us a SINAD of just 21 dB.Realizing that volume control may have something to do with it, I turned it to minimum. To my surprise, the output level actually went up and distortion down!I had not opened the unit then. Once I did, I realized that the volume pot is not for the DAC but for the headphone amplifier added to the unit after the fact. Turning up the volume on that even with no headphone plugged in, must be taxing the power supply in the unit resulting in that severe distortion.Even at this setting, the DAC finds itself at the bottom of our pile:But let's not get too fancy here. Look at the output level. They don't match! That buffer circuit they added must be screwing up the output levels. Notice also that the noise floor (in FFT) doesn't match between channels.Let' get more basic then with frequency response test:What the heck is this? Didn't the modder know to run a simple frequency response?Jitter components are quite visible although this is likely the fault of the main DAC portion:Linearity as you can expect is poor as well:It seems to be a universal truth that modders don't produce any measurements for their changes. My fear is not from them upping the quality of components, etc. It is that they screw up the basics without even knowing it. Surely nothing can be justified with respect to a box that has both low and high frequency roll off. And screws up the DAC performance so seriously if you turn up the volume on the headphone DAC.The owner tells me that people used to praise this product. If anyone did, they need to reexamine their hearing.Stay away from these mods folks. You don't allow people come to your house and take out your nice steak and put in a moldy one in your fridge. Don't do that with audio either.------------As always, questions, comments, recommendations, etc. are welcome.My wife is out for the next few days so I have to eat out for every meal and that cost money! So, appreciate you allgenerously so I remain fully nourished and can do these strenuous reviews for you using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/