What did a good 10 MHz clock do for your Gustard R26?

@magon 

It's complicated. I don't have the R26, but I do have the x26 PRO. I first added the C18 master clock to clock both the X26 and LHY-SW10 ethernet switch. It didn't make much of a difference for my Innuos ZENith mk3 streamer connected to the X26 PRO via Network Acoustic Eno III USB cable. However, I then added a DDC U18 to feed the USB cable into it and exiting via a I2s Purist HDMI cable to the X26 PRO.  And the U18 is also clocked by the C18. And WOW!!!

The sound has taken a big leap forward in every way. It's complicated because doing all these upgrades is what finally brought it all together. Exactly what did what is hard to say except that the DDC to send the USB into I2s via Purist cable was a major factor. Just adding a master clock without going any further would not give you that wow factor.

In the end, like many, I do now agree that a master clock is valuable to clock multiple pieces together but is not very effective reclocking a single unit. It only makes sense.

The overall tone of this thread reads like a warning to me. The OP is trying out a second unit because the first sounded dark and broken. Now the second unit the  imaging collapses and the highest octave is soft. I also read several other posters have added modifications to their R26s from clocks to cables in order to achieve the desired performance level. Clocks can add $750 up to $5500 to a $1700 component. I wish you luck in this pursuit. I also believe you and others will be successful due to your knowledge and dedication and obvious discerning audio talent. This one is not for me, my budget is more like spend $1700 but don't take chances @jolywins 

After having issues with the second unit if it was me I’d absolutely cut bait and move on as there are so many other excellent DACs out there.  The Denafrips Pontus jumps to mind, and adding their Iris DDC at some point will give you the ability to take advantage of its i2S connection and get a significant performance boost for not much more $$$ especially if you buy used (that’s what I did).  Just my $0.02 FWIW.

Found the best solution for my R26 was Gustard C-18 clock output to U18 DDC (set to Ext. Reference). Use good quality coax cable here. Experiment with square wave vs sine wave clock output. Sine wave output is less sensitive to cable impedance (U18 clock input is 50 ohm - make sure to use equivalent impedance cable if using square wave output). 

U18 is fed USB from server (in my case Antipodes K30). R26 gets the I2S output from U18 (make sure R26 is set to Int. Ref for clock). I2S cable supplies data and 10M externally referenced clock signal from U18. Once again -  a high quality !2S cable is important (Tubulus for me).

Sounds great to me. In this setup I believe the overall quality of the server is of greater importance and contributes more to the sound quality than the dac. I'm feeding the U18 with upsampled PCM (via PGGB - files served from internal SSD on the K30) at 705/768 kHz/32 bit. The R26 is set to NOS mode.

Dave