GUSTARD U18 DDC USB Digital Interface DSD512 PCM768Khz XU216 K2 Fully Isolation AS338 Hi-End Crystol IIS USB Audio Interface (Black)

So I have had the Gustard R26 DAC for over 6 months now. When I first plugged it in, it was a WOW moment. It had so much space, clarity and detail over my previous DAC. But as the months wore on, I found it much more to admire than to love. It was very, very controlled....maybe a bit too controlled, and although had great front-to-back depth, the sound never seemed completely unpinned from the speakers in a way I know they are capable of.So what did I do? Well FIRST I got an external clock. A modestly priced LHY OCK-1 model. By the time I added in a custom built length of LMR400 50-Ohm coax and trew in an after market fuse I had over $500 into it. Plus another $200 for a Pangea power cord.I spend weeks listening with and without the clock-something that can be done using the R26 remote on the fly. And I could not hear a single difference between running the R26 with its internal clock, or slaving it to the OCK-1. I probably would have sent it back, but since I got it on Ali Express, the return shipping would have not left me with much refund (assuming I ever got one).So then I throught I would try a risk-free trial of the U18 D2D convertor, which I got through Amazon with about an 8 week window to return it for full refund, and no shipping expenses. So I got it.Now I have the external clock, R26 and the U18.I use the USB into the U18 and the I2S HDMI cable out from it into the R26.Without any external clock, the R26 clock slaves to that of the U18's when connected with the HDMI.And that is how I first tried it...the Node N130 (with outboard DC linear power supply) -->DDC-HDMI-->R26 with no external clock.And from the very first note I knew something special was happening-which was NOT the case when I had used the OCK-1 clock. The sound was more relaxed, yet more involving with a much enhanced sense of space and timing compared to the R26 with/without external clock. And I listened to it in this way for a while.A few days later I re-introduced the external clock back into the mix. I had to get another 50-Ohm coax, but the end result was I slaved BOTH the U18 and the R26 in parallel to the same OCK-1 external clock.And BINGO....finally the external clock did make a difference. The overall presentation is quite addictive, taking everthing that the U18-R26 pairing did, and improving it in every way. Bass control and textures especially were enhanced.So now I am more than happy with what the external clock does for the R26. But do NOT get a clock before the U18, as you probably will have the same underwhelming experience as I did. The external clock should only be considered after a U18 is in place.The R26-U18 should really be considered a 2 piece integrated DAC, as the modest additional cost of the U18 only adds 30% to the purchase price, but gives an 80% boost in listening pleasure.I still have another 6 weeks trial period, but I already know-there is no way I will be returning the U18.

My audio streaming setup was an overhauled Bluesound Node 2i connected to a Gustard X26 PRO DAC. The Bluesound overhaul consisted of a package from LHY Audio with a new internal power supply board and external LPS. The difference in sound quality after installation was considerable. Still, the sound was not quite there. I read about the effect of adding the U18 to the mix and gave it a shot. What an improvement! As a system, the sound is rounder, more detailed, displays ample bass and even a bit louder at the same volume setting as before. Each upgrade, including cables, has added to the sound quality. This step, however, has had an altogether surprisingly powerful positive impact. Whereas before, SQ was a bit lacking. Now, it is where I wanted it all along. I was concerned about the need to get a fancy I2S cable to connect U18 to X26 PRO, but the U18 enables a standard HDMI cable connection between it and the same brand DAC. I am at the point where money thrown at higher priced components is unnecessary, a very nice place to be.

I opened the box and this is what I found. Heavy rubber pieces and a half ream of comp paper.

Tried with Gustard R26, no difference whatsoever. I guess if your computer does produce a lot of noise, then galvanic insulation is worth it, but technically DAC (the receiver) should be properly designed to reject it. Perhaps R26 is, indeed, properly designed.

The Gustard U18 is a wonderful addition to Gustard X26 Pro. The sound is very natural.

First, for those who want to understand how DDC is connected in the digital audio system:USB Streamer (such as PC) > DDC > DAC > Amplifier > Speaker.USB streaming is NOISY. It has tons of electric distortion and digital jitter which makes your computer audio, especially its background and higher treble, have that sharp bite which fatigues the ears.Although both DAC, preamp, and amplifiers all produce their own digital distortion, this DDC is designed to at least "purify" the digital sound before it sends them to the DAC. In other words, this DDC purifies the USB signal coming from the streaming source.DDC such as this achieves this in two ways, first it removes the electrical distortion by separating the USB signal and powering it with its own "clean" toroidal transformer. Second, it uses its excellent internal K2 femto clock to precisely time-aiign the digital signal, which effectively removes the digital jitter.I have used both the I2S and toslink outputs and both are excellent.So how does all this impact the sound? The sound would come off as noticeably clearer, the background would be far more darker, and your ears would be able to listen to music without the normal discomfort and airbite associated with digital music. In short, this can make your digital music sound like analog but with the dynamic range and imaging of the digital music (assuming you have decent DAC, amp, and speakers). Sounds like a good investment? Yes it is.Pros:1)All but eliminates electrical and digital jitter distortions. This means much more clear sound with detailed imaging you can hear without interference.2)Has an impressive Femto clock that precisely aligns digital signal prior to sending it to DAC, resulting in precise and detailed music without the glare associated with digital music.3)Extremely great value for the money.4)Fairly small (little larger than a cracker jack box).Cons:1)Build quality isn't top notch but what do you expect for a lower priced DDC?

Wow! This little box changed the sound. It is close to perfect!