Gustard R26

Hi guys, first post here.

@kairosman I have the R26 and recently became one of those guys with a couple of inline switches. I found inserting a modestly priced Netgear GS108E (albeit Alpha Audio recommended) upstream of my already very good LHY SW-8 gave a nice improvement in soundstage focus and tightened up the bass of my R26-based system. I have yet to try FMCs but have found the R26 LAN input / renderer (I use its HQPlayer NAA) very sensitive to and able to resolve all upstream ethernet chain improvements I've made. This includes for e.g. adding Quartz Acoustics grounding boxes on my server, switches and router. I have a couple of Ifi LAN iSilencers (galvanic isolator & USB regenerator) on order to further optimise things after some early very positive feedback from a few folk with already well sorted systems.

I concur that adding a decent clock like the LHY OCK-2 to the R26 lifts it to another level, particularly when used with a high quality clock cable like the 50 ohm Harmonic Technology DC III or better. When the R26 LAN input is selected I understand a connected masterclock will be used by the R26 to clock both its renderer and DAC sections. This may explain in part why I find the sound of R26's HQP renderer superior to that of DDCs I own like the U18 and SU6, even when the U18 is also externally clocked.

@kairosman With respect I didn’t say the R26 uses an external clock to reclock its DAC section only with the LAN input selected but that when the LAN input is used it also reclocks its streamer/renderer section. So it’s just there’s a there’s a dual benefit in my use case.

I’ve verified through careful AB’ing (ext clock on/off toggling) that the R26 does audibly benefit from an R26-connected external clock when fed I2S or S/pdif from the SU6 or U18, irrespective of whether DSD Direct or PCM NOS is on or off. From recollection others on Headfi found the same with the R26 and the other Gustard *26 DACs that share the K2 clock synthesiser.

@arafiq I use the R26 streamer with Roon and HQplayer, faultless operation and sounds great. I use HQP upscaled PCM768 & DSD512.

I prefer the sound of the R26 internal streamer to my Ifi Zen Mini (+ IFI Power X) > Gothic Audio pure silver Outsider USB cable > Gustard U18 DDC > BJC FE I2S > R26. I actually found using a USB direct connection from my server to the U18 (albeit with the Holo Titanis USB regenerator plugged into the server) to be better than the Zen > U18, and closer to but still some way behind the R26 internal streamer. With an external clock in play the gap widens.

That said I know of a few folk with better streamers (like the Ifi Neo Stream) or servers (such as with $2k JCAT USB & ethernet upgrades) who prefer I2S and/or USB connection to the internal streamer. 

@Kairosman - from my reading the conventional wisdom is most DACs when fed sources like I2S, s/pdif and AES that contain a synchronous word clock will use that embedded clock signal untouched so theoretically at least a master clock connected to the DAC wouldn’t be used to reclock the stream so would be of no benefit. And that conversely with asynchronous sources like USB and ethernet they are of necessity reclocked by the recipient DAC/ streamer and so if the DAC/streamer is being slaved to a master clock you’ll get the benefit of its greater temporal precision. Indeed from memory Gustard’’s R26 product blurb that appears on vendors’ sites is consistent with this referring to the USB and Ethernet inputs being reclocked.

So far so logical. But then it gets rather less clear cut with:

a) a clarification Gustard provided over email to a Headfi member (copied verbatim below, ambiguous punctuation and all) that suggests - depending on how you read the punctuation - that all the R26’s inputs benefit from an external clock with NOS & DSD DIRECT OFF (ie over sampling ON) but with NOS/DSDD ON only the asynchronous inputs, USB and ethernet, benefit; and

b) at odds with a) my observation from careful testing that there is a satisfying audible benefit of toggling an EXT Clock ON for I2S and s/pdif regardless of the NOS/DSDD setting. Fairly sure a number of other Gustard *26 owners who use I2S and NOS/DSDD also find a good benefit with an external clock. As to the mechanism of action/benefit from the external clock if these synchronous inputs are not buffered and reclocked (which would seem unlikely), your guess is as good as mine!

It has become apparent there’s substantial language barrier/translation error risk factor with any comms with Gustard, so a pinch of salt with all their comms and publications especially on nuanced technical points is wise. Eg. They accepted the manual had a translation error re DSD processing.

Credit to HF member MMWMM:

This is an answer from Gustard regarding the use of a 10Mhz external clock with the R26 and when its clock signal is used to reference the internal K2 synthesizer and when is not used.

“When playing PCM

1. PCM NOS: OFF
The improvement provided by the external clock applies to all R26 inputs.

2. PCM NOS: On
The improvement provided by external clock applies to USB and LAN inputs, IIS AES coaxial optical Bluetooth does not apply.

When playing DSD

1.DSD DIRECT: OFF
The improvement provided by the external clock applies to all R26 inputs.

2.DSD DIRECT: ON
The improvements provided by the external clock apply to USB and LAN inputs, IIS AES coaxial optical Bluetooth does not apply.”

@kairosman Nothing more exotic right now alas. My only point of comparison was a head-to-head with a similarly priced and since returned SMSL AK4499 VMV D2 DAC last year, which the R26 beat handily. Oh and a Topping E50 they both destroyed. R26 & D2 were using the Zen/U18, Roon/HQP and an Ock-1.

All I know is that my R26’s sound has improved out of sight since then with network chain improvements, better external clocking and signal grounding (I can’t recomment Quartz Acoustics Premium grounding boxes highly enough). If the ’stock’ I2S input R26 YT reviewers compared favourably with R2Rs up to maybe the level of the Pontus/Venus and the Spring 3, then I reckon (he says, perhaps a little optimistically) in my more optimized setup it’d now surely soar well past them, if perhaps not quite as far as your Baltic 4...