Opticalrendu vs. direct connection PC with audiophile USB card

I was hoping to get any thoughts on the following.

I have built an Windows-based Audio PC running RoonCore with a audiophile USB card with its own high-end OCXO-clock made by a guy named Paul Pang. Both the PC and the USB card are powered by an external linear PSU from HD Plex. The internal power-unit of the PC is also a fanless low noise DC-AT unit from HDPlex. The PC contains only m.2 ssd drives, so not spinning parts or unnecessary cables. It is also running various audio optimisation software packages (Audiophile Optimizer and Fidelizer Pro).

This set up is now connected directly by USB to the Chord M-Scaler, which in turn is connected to the Chord Hugo TT2 by two BNC cables.

I recently found out that the Denon AVR in my setup, which is connected to the Roon core through an ethernet connection and a Netgear switch, also acts as a Roon endpoint. This allowed me to do some A/B testing between the ethernet-connected Denon and the USB-connected Chords. Much to my surprise I found myself sometimes preferring the Denon. While it does not offer the control and precision of the Chords, it at times offered a more powerful sound at the same volume levels. Especially in more bass heavy music, the Chord can sound more constrained.

This has me thinking that maybe I should consider hooking up my Chords through an Opticalrendu endpoint, which would effectively isolate it from any noise my PC might introduce (which I had assumed would be minimal). My PC and switch are already connected through fiber, and the switch still has an available optical port, so it is an easy enough tweak to introduce.

My question is: do you think this would make much of a difference, given the specifications of my current audio PC?

I am also aware of the OPTO-DX solution which adds a fibre firewall between the Chord M-Scaler and Hugo TT2, but I don’t see how that can fix distortion if it has already been introduced into the M-Scaler by the USB-signal from the PC.

Any tips, feedback and experience is very much appreciated!

Of course the problem might also be that I simply prefer the more distorted sound of my simple Denon AVR Dac, but let’s ignore that possibility for now ;-)…

My original setup was a CAPSV3 Zuma ‘audiophile’ server connected via a custom USB card to my MSB DAC with a USB input.
I ‘upgraded’ to a NUC8i7 running ROCK and replaced the USB input on the DAC to an Ethernet Renderer. In order of importance of perceived improvements:

  1. I now have less hardware in the room and it looks neater. Yes, this is the major improvement for 2 grand.
  2. With the USB out of the equation I no longer feel compelled to chase USB cables. Never got that bad, now it never will.
  3. Thanks to the Ethernet Renderer having MQA decoding, I now recognize there is no important difference between a good 24-bit recording and the same music via MQA.
  4. Sonically, I don’t believe there was much of a difference. Maybe, but I doubt I’d pick them out blind testing.

So, I am of the belief that if you have fundamentally good hardware to start with, there isn’t a reason to chase this. That said, there will be enough others that claim the opposite. The only way to resolve this is to trial one and see for yourself. Next best is to buy one used so you can sell it without taking a bath if you are not impressed.

Do you mean you were hooking your TT2 output to your Denon AVR’s analogue input?

For comparing with the Denon’s ethernet input?

If your Denon is doing DSP (like Audyssey) it will be digitising your Chord output, then using Denon’s internal DACs. So you’d have double D-to-A with A-to-D in the middle.

Thanks, that sounds like good advice, I’ll keep my eye out for a secondhand or discounted one.

No, sorry if I wasn’t clear. The Denon is networked through ethernet, and my Roon-core recognises it as an endpoint, which is entirely separate from the Chords-endpoint. This allowed me to stream the same song to both endpoints, and change the selection on my (separate) Primare pre- and end-amps. This should result in a pretty close comparison of just the DACs (i.e. the Chord vs. the one that’s integrated into the Denon AVR).

You make a good point about the DSP on the AVR. Let me doublecheck if that can be switched off.

Oh right.

How does your Denon connect to your Primare amps? Via the Denon’s pre-outs?

you are right, although it is just the pre-amps that are different, all signals go through the same end-amp to the speaker.

Be sure to at least switch the Denon to ‘PURE DIRECT’ mode for your comparison.

Some people send a lot of time and money tweaking the music server in an attempt to make it less noisy. The Rendu is meant to be a remote output in the audio room far away from a noisy (electrical/mechanical) music server. The Rendu is small, custom built, and a clean source that is isolated from other gear on the network. With a Rendu the source can be a computer, music server, NAS, or streams from the internet. There is nothing to optimism and you just use the best power supply you can afford with the Rendu.

IMHO an amplifier upgrade with your Chord M-Scaler and Chord Hugo TT2 would be something to consider next. The opticalRendu is fantastic in combination with the Chord gear.


Thanks Jesus, the Chords are connected to a Primare Pre- and Power amp for hifi listening. I use the Denon AVR only for home cinema or if I want to listen to music with the subwoofer (using the AV bypass function in the Primare Pre amp). I am generally very pleased with the sound of the Chord combo, but it just struck me that sometimes I preferred the Denon. Like a previous poster noted, this probably has to do with the DSP my Denon was doing, which I failed to take into account.

Nonetheless, I ordered the OpticalRendu to see what it would do, as it will allow me to put a fire (fibre?) wall between the PC and the Chords. Looking forward to trying it out.

It’s hard to explain personal taste and perception:) Welcome to the Rendu family.

Cool, definitely report your findings. The direct to DAC vs.endpoint is a never-ending discussion and many times goes to either extreme, like many audio topics. It’s really system / individual dependent and is something you’ll have to decide - which is what you are doing, so that is great.

It goes without saying the PSU for the OpticalRendu (any endpoint or pretty much anything audio) is very key so hopefully you have that base covered for your eval. If you are using media converters also try and have decent PSU as well. Most of all have fun


One thing I have found out makes a massive difference over the years, is how you’ve got everything plugged in. That includes power, ethernet and interconnections between components.

You should really make sure that nothing connects your AV receiver to your stereo set up, Because that can transfer noise to your stereo even if the receiver is not switched on, and AV receivers can be very noisy. If it is, that maybe a reason why you don’t notice too much difference, maybe.

I have found out, and still am today doing little tweaks, that noise transferred across components is very detrimental.

I have had great improvements in isolating my hi-fi set up from everything as much as possible, to eliminate as much noise being transferred as possible.

Ethernet is very good at transferring noise across your equipment, so although having some components connected to your router can be very handy and cool, if they’re not necessary I would not plug them in and allow them to transfer noise. Or if you need them for the occasional updates just plug them in when you need to do an update, then unplug them again.

Everybody’s system, house, network and electrical supply is different, so it’s always an individual project to look at how everything is connected to what, because noise can travel along conductors linking your components, Even if some of those components aren’t switched on. Especially Ethernet, which can transfer noise through components that are even switched on.

For example, only the other day I decided to move the power supply for my opticalmodule to a different ring main circuit from the fuse board, to separate it completely from hi-fi set up and OpticalRendu…
before I moved it, it must’ve been transferring some noise from the ethernet circuit to the opticalmodule, From opticalmodule to power circuit and back to hi-fi.
The sound stage on my hi-fi just opened up massively, and sounded softer but still detailed.

It’s amazing what improvements in just a little simple adjustment to reduce noise being transferred to your hi-fi set up can make.

Possibly a reason why hi-fi sound is so diverse, even if two people have the exact same components, they can sound so different.

Yep! Works great in my setup. I run Roon server on my iMac in the office. No special audiophile tweaked ethernet switches or other hardware necessary. I have added a Pink Faun LAN Isolator before going into the opticalModule and use a Sbooster linear power supply for the opticalModule and the opticalRendu. Everything before the opticalModule in the chain can be ignored, including Roon server. As long as it has enough performance and delivers the data, there is nothing to be optimized.

I hope you have a good PS on the Rendu:)

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The same. Sbooster for opticalModule and opticalRendu each. :wink: