Simple Design Rendu Ethernet to S/PDIF Converter Review

High end audio can be a polarizing hobby. Audiophiles like to select a product or technology and support it vigorously as if they have a large financial interest in its success. I was born an audiophile. I completely understand the desire for one's selection to be validated by the audiophile community. I also completely understand how unhealthy that desire for validation is and the neurosis it can cause. Audiophiles, myself included, must realize the products we select today will sound just as good in five years regardless of competing products, newer technologies, and others' opinions. One polarizing topic in computer audio is digital interfaces. Two digital interfaces that have strong vocal support from users are USB and Ethernet. Users of one technology frequently turn a blind eye to the merits of the other technology and won't even consider its use. Many users selected one technology a few years ago based on the information available at that time and refuse to update their own knowledge for any number of reasons. This leads to armchair engineer arguments based on half truths and old information. These discussions are a disservice to all readers. Based on my experience with both USB and Ethernet interfaces it's clear to me that both can sound excellent and both will have a strong presence in high end audio for the foreseeable future. One Ethernet interface that caught my attention a couple months ago is the UPnP AV 2.0 / DLNA compliant Simple Design Rendu Ethernet to S/PDIF Converter. Admittedly I was drawn in by the features and specs, notably its ability to play DSD, 24/192 PCM, and gapless audio streamed over Ethernet. I've since listened through the Rendu for countless hours and put it through a number of network audio tests. At first the Rendu was a bit picky and had some playback issues. Today using the newest firmware I'm happy to report the Rendu works very well and continues to sound very good. The Simple Design Rendu Ethernet to S/PDIF Converter is a product to watch in both two channel and whole house network audio. [PRBREAK][/PRBREAK]

Simple Design Rendu Ethernet to S/PDIF Converter

The Simple Design Rendu is an Ethernet to S/PDIF all digital converter. The Rendu could be considered an audio appliance. It has one switch on the outside that turns the unit on/off and zero user configurable options. The Rendu is simple to understand. Ethernet in, S/PDIF out. Its only input is an Ethernet port that's connected to a home network via CAT5 or better cable. Its only output is a transformer coupled true 75 ohm BNC S/PDIF port that connects to a Digital to Analog Converter (DAC). Connecting to a DAC with an RCA S/PDIF port requires a very inexpensive BNC to RCA adapter. Simple Design can also supply a Cardas BNC to RCA cable. In addition to the Ethernet to S/PDIF model reviewed here Simple design offers an HDMI i2s model and a version with a built-in DAC among others.

The Rendu features a low noise, low output impedance linear power supply. This power supply no doubt has roots in the extensive research Simple Design has done for its USB converters and Sonore music server PSUs. Critically important in converters such as the Rendu is the clocking scheme. Simple Design uses two fixed frequency low jitter clocks in the Rendu. This is frequently seen as one of the best, if not the best, way to lower jitter. One feature that may seem un-audiophile at first blush, but is very nice, is the integrated, 32 bit, high precision volume control. I really like this feature for controlling volume in independent zones. For example, when using several Rendu units and streaming the same or different audio to each unit it's possible to control the volume from an iPad / iPhone app such as JRemote. Using JRemote enables the user to not only control the volume of each zone independently but also from anywhere in one's house as long as the iDevice is on the network. During the review period I spent limited time with the volume control feature as my main use was two channel audio where my preamp remote was always available. In the next week or two I will publish a complete article on multi-zone audio using several Rendu units. In this upcoming article I will touch on the digital volume control of the Rendu.

Careful selection of internal components by Simple Design enables the Rendu converter to stand out with a great set of features that work. Fans of Ethernet audio understand very well that UPnP / DLNA audio renderers often fail to meet the marketing hype from many manufacturers. The Rendu Ethernet to S/PDIF converter can do everything as advertised by Simple Design. This is a company that understands computer audiophiles and the Internet. Simple Design knows people will rant far more than they rave about a product. If the Rendu doesn't work as promised the company will never hear the end. A few of the Rendu's great features are DSD / DoP support for DSF and DFF files, 44.1 through 192 kHz support, AIFF, ALAC, WAV, and any FLAC compression level support, and (the mother of many heated internet rants) gapless audio support.

The Rendu digital converter has some specific requirements in order to use its full potential. The Rendu hardware is ahead of most software applications with its DSD / DoP streaming capability. Readers looking to use the Rendu as a simpler PCM only converter without gapless support can likely use almost any UPnP / DLNA server / controller combination to feed audio to the unit. I have several DSD albums and live albums that require gapless playback for full effect. Thus I setup my system to meet the Rendu's requirements (at first). Then I strayed from the requirements and succeeded in producing a better user experience with my own configuration. According to Simple Design, "Gapless is currently supported via Android with Bubble UPNP as controller, J-River on PC and Mac as controller with local storage." In addition, "DSD/DoP pass thru requires the use of MinimServer." Once I verified the aforementioned configurations worked OK I moved to my preferred setup that I knew would also work. I used JRiver Media Center v18.0.175 as the server and an iPad with JRemote v2.31 as the control point. All my music is stored on a Synology DS1812+ NAS that isn't running any UPnP / DLNA software. JRiver's newest Media Center build features what it calls Bitstream DSD. This feature must be enabled deep within the Media Network settings for Media Center to stream DSD content as DoP to a compliant device. DoPE (DSD over PCM Ethernet) is supported by JRiver Media Center and MinimServer with the dopwav transcoder option. I used both during this review, but mainly JRiver because I like all its features, support forums, and using JRemote. The Simple Design Rendu supports gapless playback using SetNextAVTransportURI. There are other methods to accomplish gapless playback but I believe using SetNextAVTransportURI is the best method. JRiver Media Center sends a SetNextAVTransport call to the Rendu and identifies the upcoming track. It's then up to the Rendu to play the next track gapless. I put the Rendu through the ultimate torture test by attempting to play a gapless DSD album. Let's just say playback was a little less than great, but I believe JRiver Media Center had a hand in this subpar performance as well.

Note: No question is a dumb question. Some readers have asked what is gapless playback. Gapless playback is simply playing the tracks on an album or in a queue without a time gap between tracks. When listening to The Dark Side of the Moon the tracks bleed into each other as do the tracks on most live albums. Without gapless support there is a pause of one or two seconds while the next track loads before playback continues. Gapless playback eliminates this time between tracks for smooth playback of all tracks just as the artist intended.

Testing Rendu's Features

The Rendu not only had to sound good it had to work as advertised. Playback of 16 bit / 44.1 through 24 bit / 192 kHz material may seem like a standard feature that should work on every device, but that's not the case. Many UPnP / DLNA devices based on the Stream Unlimited Stream 700 board have a difficult time playing uncompressed FLAC files at 176.4 and 192 kHz. The Rendu doesn't use the Stream 700 board and doesn't have any problem playing 24/192 material bit perfect. The ability to play all relevant sample rates in whatever file format I use is a big deal. Devices that require transcoding one's entire library to a different format or compression level can tun off potential users and steer people from network based audio for no good reason. I connected the Rendu to my Berkeley Audio Design Alpha DAC for much of the testing as this DAC enables me to check for bit transparency. The sound quality of the Rendu was very good in my Berkeley / Spectral / TAD system. I really didn't know what to expect as I've never seen measurements for this device and I've only heard from Simple Design about the sound quality. Based on my extensive listening to the Rendu it's a terrific converter at all PCM sample rates.

DSD over PCM Ethernet (DoPE) is a feature that intrigued me very much. At first I asked Simple Design why I would need this because the DoP devices I had used were all USB based and the Rendu was S/PDIF. Simple Design said DoP isn't interface specific and will work on S/PDIF, USB, and AES. Once I learned that major piece of information I was on a mission to find a DAC that supported DoP on its S/PDIF inputs. As luck would have it the dCS Vivaldi stack with DAC, Upsampler, and Clock arrived shortly thereafter. The Vivaldi DAC and Upsampler both support DSD DoP on all inputs. With the Vivaldi in place I could test the Rendu's DSD playback capability and sound quality. Much like it was with PCM the Rendu sounded very good with DSD material. My usual Nat King Cole album The Very Thought of You streamed via DoP from my computer to the Rendu then through the Vivaldi Upsampler was impressive. My only problem with DoPE playback was related to software. When selecting a DSD track playback started in JRiver MC but sound didn't come through the system for about 15-20 seconds. The tracks suffered a majorly delayed start, but weren't shortened in any way. MinimServer didn't produce this long of delay but my MinimServer library was vastly different as it resided on my Mac with five albums. Right now I consider MinimServer a testing tool because the JRiver interface with JRemote is so much better. However, for many people MinimServer is perfect because it is very low profile as it runs in the background and can be directed at a user's existing iTunes library. Perhaps if DoPE was of great importance to me and much of my collection was DSD encoded I would switch to MinimServer. I'm willing to bet JRiver will improve DoPE streaming in the coming weeks and months. The feature was only recently enabled. Without many test users for such a feature it's hard to get user feedback for improvement in a short period of time.

Note: The EMM Labs DAC2X doesn't support DoP on S/PDIF or AES inputs yet. I've been told the Mytek Stereo 192 DAC and Benchmark DAC2 HGC support DoP on S/PDIF and AES inputs.

Gapless playback over Ethernet has been the bane of many manufacturer's existence. Thus, I tested gapless playback extensively throughout the review period. The original version of Rendu firmware didn't support gapless playback. Simple Design furnished a firmware update, version 1.36.1.5, that enabled gapless playback at all sample rates. My music library contains gapless albums of all sample rates from 44.1 through 192 and even DSD. As noted earlier gapless DSD didn't work, but I don't hold that against Simple Design and the Rendu. I started with simple 44.1 albums such as The Dark Side of the Moon. Rendu didn't blink upon each track change. Playback was gapless or seamless from Dark Side track to track. I moved up to The Dark Side of the Moon at 24/96 ripped from the Blu-ray in the Immersion Box Set. My experience was identical to playing 44.1. The Rendu didn't blink and the sound was very good. After playing some gapless 24/176.4 material I moved to Stevie Ray Vaughan and Albert King at 24/192 kHz. The entire album start to finish played gapless through the Rendu. I also stopped and started a few tacks to simulate what a real user may do while listening. The Rendu / JRMC combo performed flawless. I thought I'd find issues with gapless as I moved up in sample rate. Fortunately there was no difference in gapless performance from 44.1 to 192. There was no way to identify the sample rate of the current album based on gapless performance. Either it's gapless or it's not and the Rendu is gapless at 192.

Near the end of the review period I connected the Simple Design Rendu to the EMM Labs DAC2X's S/PDIF input and my CAPS Carbon server to the DAC2X's USB input. I wanted some reference with which to compare the sound quality through the Rendu. This comparison isn't the most real world comparison as most people with computers within 16 feet of their audio systems will simply select USB. The remaining users must user a longer distance technology like Ethernet. I don't see the Rendu as a competitor to products like the Berkeley Audio Design Alpha USB converter because the technologies are like apples and oranges. Users will likely require one or the other. During the comparison I was able to move directly from the USB to S/PDIF input and back with ease because the EMM Labs 2X remote has discrete input selection. I much prefer long term listening to compare components, but I did both short and long term for this review. Overall the Rendu holds its own very well versus the USB input of the DAC2X. Readers should consider that the 2X resamples all data to DSD rates as part of its jitter reduction scheme. I don't know if this equalizes the sound quality of the inputs a little bit or majorly. Music via the direct USB input was a bit tighter with a more solid image. When switching between inputs the first thing I noticed was the tightness of the images when using USB. I don't mean smaller image or soundstage rather the sound in the image just appeared tighter. The other noticeable sonic difference was a slight soft edge at the top and bottom frequencies through the Rendu. This softness was really minor. It's likely that many users wouldn't notice it unless presented with these two options for comparison and very familiar music. The Rendu was at a large disadvantage because the direct USB input is asynchronous and controls the clocking. Yet music played through the Rendu sounded very good. This is a terrific Ethernet to S/PDIF converter that works and sounds very good.

Conclusion

The Simple Design UPnP AV 2.0 / DLNA compliant Rendu Ethernet to S/PDIF Converter is a fairly unique device. Its features such as true gapless support from 44.1 through 192 kHz and DSD DoPE playback for streaming DSD over Ethernet help set the Rendu apart from the competition. Features are one thing but sound quality and a device that delivers on the manufacturer's promises is another. The Rendu sounded very good in all systems I used during the review. Both PCM and DSD playback was impressive through the Rendu. It's linear power supply likely plays a significant role in its sonic quality. The Rendu delivers on all its advertised features from DSD to 24/192 PCM playback to gapless audio all streamed over Ethernet. These features simply work as they should. The Simple Design Rendu Ethernet to S/PDIF Converter is a great solution for Ethernet based audiophiles, those tempted by Ethernet audio, and multi-zone music aficionados among others. Highly recommend and CASH Listed.

Product Information:

• Product - Sonore Rendu Ethernet to S/PDIF converter
  
• Price - $1,369
  
• Product Page - Link
  

Associated Equipment:

• Source: 15" MacBook Pro w/ Retina Display, C.A.P.S. v3 Carbon Server
  
• DAC: EMM Labs DAC2X, Berkeley Audio Design Alpha DAC Series 2
  
• Digital to Digital Converter: dCS Vivaldi Upsampler
  
• Preamp: Spectral Audio DMC-30SS Series 2
  
• Amplifier: Spectral Audio DMA-260
  
• Loudspeakers: TAD Labs CR1 Compact Reference
  
• Remote Control Software: JRemote, PlugPlayer
  
• Remote Control Hardware: iPhone 5, iPad (3rd Generation)
  
• UPnP Software Windows 8 and OS X 10.8.3: J River Media Center 18, MinimServer
  
• Cables: MIT Matrix HD 60 Bi-Wire Loudspeaker Cable, MIT Oracle Matrix 50 Analog Interconnects (RCA), ALO Audio AC6 Power Cables, Wire World Silver Starlight USB Cable, AudioQuest Diamond USB Cable
  
• Network Attached Storage (NAS): Synology DS1812+
  
• Network: Cisco SG200-26 Switch, Baaske MI-1005 Ethernet Isolator, Micro Connectors Augmented Cat6A Ethernet Cable, Apple AirPort Extreme, Cisco RVS4000 Router, Cisco DPC3000 Docsis 3.0 cable modem, Comcast Extreme 105 Mbps Internet Service