It's been awhile but I made a promise to someone that I would submit this post and so here goes. I have not kept up faithfully with this thread or any other thread but friends have periodically brought certain important findings to my attention and so I am aware of how splendidly so many of you have continued to push the envelope with regards to digital. It's nice to see that the spirit that this thread was founded on remains vibrant and strong. Thanks especially to Rajiv for continuing to moderate this thread so ably.
Much has changed with my own system since I last posted. While I have largely retired from posting due to other time commitments, my curiosity for the unknown aspects of digital continues to burn strong. I have no scientific explanation for so many differences that I hear but as best as I have been able to figure out, good digital amounts to 3 things: (1) low noise, (2) low impedance, and (3) low latency. Maybe there are other characteristics I have left out but as I have attempted to improve my own digital setup, I have sought to address primarily these 3 things.
As those who have followed this thread from the beginning are aware, I put together my own single chassis server some time ago and it was the very best I knew how to do. Foundational to this server were a modified DFI motherboard, 7 SR7 rails, 9 clock replacements (from the router all the way to my final endpoint just before my DAC), and a REF10 that tied all these clocks together. My OS of choice was Windows Server 2016 running off an Intel X25-E SLC SSD which was further refined with AO/Process Lasso/Fidelizer Pro. Roon was my player of choice. What I got was smooth, harsh-free digital playback with robust dynamics. Sitting atop a Synergistic Research Tranquility Base, I was pretty happy with this setup...for about 3 months.
Then came along the Innuos Zenith SE and it highlighted some important deficiencies in my system. While my server brought about a greater sense of resolution and less harshness thanks in large part to all my clock replacements and the REF10, the SE displayed superior dynamics, even with my SR7 powering my server. Having taken apart my SE and carefully examined what went into this build and having spoken with Nuno of Innuos and Sean Jacobs, the SE's PSU designer, it became clear to me there were several reasons for what I was hearing but a big reason was the SuperMicro board they chose was superior to the DFI motherboard I used with my build. With the SE followed by my tX-USBultra powered by a DR rail from my SR7, this was now my very best setup and so I purchased an Innuos Zenith SE. I was pretty happy with this setup...for about 6 months.
There remained a subtle harshness with my digital setup that was tolerable in my large listening room where I had my large Martin Logan Renaissance electrostats but less tolerable in my nearfield Voxativ setup. Voxativs have a tendency to run bright and so any HF harshness tends to get magnified with these speakers resulting in fatigue. When I swapped out the SE for my old modified Mac Mini that ran MacOS off an SD card, this harshness went away but it was at the expense of vibrancy and immediacy. There was a definite tradeoff. I swapped in my other modified Mac Mini that ran Windows Server 2016/AO off an integrated PCIe NVMe SSD and the vibrancy and immediacy came back but the harshness was even worse than the harshness I heard with the SE. Just like in the past, after 5-6 hours of listening, there was fatigue. In my view, it had to be the SSD that was the culprit. According to Ed Hsu of Sound Galleries, SSDs emit a noise in the 6GHz range that is very difficult to filter and the faster the SSD, generally the noisier it is. Based on what I was hearing, I had no reason to doubt what he was saying.
Late last year, I was introduced to Adrian Wun, owner of The Linear Solution (TLS) by a fellow CA member. Adrian was designing his own server that incorporated the same SuperMicro motherboard used in the Zenith SE although he modified this board with multiple OCXO replacements and powered it with his own custom designed multi-rail ATX PSU. What really intrigued me was his custom OS, basically a modified and purposefully-tuned Linux OS that he compacted down to a size below 6GB and so he was able to completely run this OS from memory. With this OS completely running from 8GB of RAM vs a PCIe NVMe SSD, he said latency improved by a factor of 10-150x depending on what processes were running. I filed this little tidbit into my own memory because I knew I would want to eventually explore this.
A New Motherboard Discovery
My Innous Zenith SE experience taught me what many others on CA had known for some time, that performance is likely to improve if the CPU and the rest of the motherboard are powered independently. This means that my DFI motherboard was being crippled by the single 12V DC feed that was powering the entire board. In my mind, if I was to one day build something even better than the SE, I would need to target a motherboard that provided independent power to the CPU which meant I would be forced to using an ATX PSU (or at the very least, a DC-ATX converter). Paul Hynes told me he would one day get around to designing one but he had too much on his plate to know when this would happen. Sean Jacobs told me he could build one for me immediately. As the Zenith SE I owned already incorporated one of Sean's wonderful designs, I figured my best bet was to stay put, however, I continued to be on the lookout for better motherboards that would allow me to completely do away with an SSD.
Earlier this year, I came across a particular Intel NUC motherboard that incorporated a certain feature that has intrigued me for some time. This motherboard is the Intel NUC6CAYB and here is that motherboard:
What intrigued me about this board is its use of an eMMC device for OS storage. This is 32GB of solid state storage that is "embedded" onto the board that is as electrically quiet as an SD card but has "near" the speed of a typical SATA III SSD. Other features include an embedded low power Celeron CPU with an SoC architecture and up to 8GB of RAM capacity. Unfortunately, there was no way to power the CPU independently as this board takes a single 12-19V DC feed, however, given the very small 4" x 4" size of this UCFF (Ultra Compact Form Factor) board, I figured it should have even lower impedance than a larger mini-ITX board and was worth $100 to test it.
I was able to convince Adrian to "loan" me his customized OS for this build and so while his OS is permanently stored on the eMMC drive, upon boot up, this OS transfers completely into 8GB of RAM and so the eMMC drive serves only as a place to store the OS when the server is shut down. While you could argue that I could have used an SSD drive in this situation and that the SSD would sit idle since the OS would be running completely from memory, my contention is that even a dormant SSD still generates noise. In the end, the proof is in the listening.
With Adrian's Dream OS loaded onto this board and running completely from RAM, with Roon Server running as the sole app, and with this inexpensive server powered by a DR rail from my SR7, I was hoping it would come close to my Zenith SE with respect to dynamics but improve upon the SE with respect to less HF harshness. I was not prepared to discover that this setup quite soundly bettered my $7k SE in every way. Unlike my DFI board, it was as if this board was allowing my DR SR7 to really show what it could do. Dynamics were superior to the SE. Transients were cleaner. Immediacy and tonal vibrancy were better and with none of the harshness! I compared this NUC board against both my modified Mac Minis and against my custom server and this new build easily bested both Mac Minis. Against my previous custom server, the perceived detail resolution was still superior with my custom server due to all the clock replacements but dynamics were easily superior on the NUC. If I followed the NUC with my tX-USBultra/REF10, this was now my very best setup. So good that I have sold my SE.
But Wait, There's More...
I tend to follow the product offerings of many music server companies to see what new innovations they have come up with and I noticed that earlier this year, Antipodes announced their new flagship was now a dual PC setup called the CX + EX, basically a server + renderer combo instead of the single box DX Gen 3. I found 2 things to be interesting:
(1) Mark Jenkins felt that splitting up server and renderer duties between 2 machines resulted in superior SQ compared to a single PC functioning as both server and renderer. This is not an entirely original concept as JPLAY has been championing a dual PC setup for years based on this premise. Moreover, devices like the original microRendu have popularized the concept of a separate server and a low power NAA or Roon endpoint for some time.
(2) Mark decided to employ the "direct Ethernet connection" via bridged LAN ports between the CX and EX that many of us who have been following this thread since its inception began employing some time ago. In his words, this direct Ethernet connection "provides a dramatic improvement over connecting your server and renderer through a noisy switch or over a long length of network." Good for Antipodes.
While neither of the 2 concepts above are original, Antipodes is the first server commercial manufacturer that I'm aware of that is not only advocating both concepts simultaneously but is also selling a turnkey setup that incorporates both setups and unlike an ultraRendu or sMS-200ultra that are incapable of running standalone, both the CX and EX are standalone PCs meaning if the owner chooses, they can run either one without the other.
This really got me thinking. While I left my SOtM trifecta some time ago because I preferred a more elegant single box solution, I decided to run my NUC as a Roon renderer only (Roon Bridge) and my Zenith SE as a Roon Server. With both connected to my network via the standard "indirect" method, there was certainly an improvement in terms of "less edginess" but the improvement was subtle. With the two connected directly via bridged LAN, the improvement in SQ as far a "less stressed" sound but also better transparency was more pronounced. Of course, to relegate the $7k Zenith SE for server only duty didn't sit that well with me and so I decided to swap out the Zenith SE for my unmodified Mac Pro with 12-core Xeon, 64GB of RAM and 1TB of PCIe NVMe SSD to see how much degradation in SQ I would get and the degradation was indeed significant with respect to harshness. This was the exact same observation I reported early on in this thread, that the direct Ethernet connection is not only more transparent to the qualities of the upstream server but also more transparent to any inadequacies that upstream server may possess.
At some point during my testing with SE as server and NUC as renderer, I decided to move my SE into my home office where my near field Voxativs were kept while keeping my NUC in my larger listening room with my Martin Logans. To directly connect these 2 devices, I had to run 53 feet of Blue Jeans Cables CAT6A Ethernet cable in my crawl space and that is exactly what I did. While the improvement was still quite desirable, it was not as pronounced as what I had experienced with my SOtM trifecta which consisted of an sMS-200ultra, a cheap SOtM-modified switch, and a tX-USBultra. As I first described my experience with installing a reclocked switch into this "direct" pathway early on in this thread, I found the impact of this switch to be dramatic and nearly on par with the tX-USBultra and so I knew that I needed to throw in the switch.
The Importance of the Network Switch
There was no doubt in my mind that introducing a reclocked switch into this direct pathway between the SE and the NUC would result in further improvement but I was curious to know if the impact would be greater with the switch connected closer to the SE vs connected closer to the NUC. Keep in mind that these 2 devices are separated by 53 feet of BJC CAT6A cabling and I never had to contend with this length of cabling with my SOtM trifecta. Most would probably guess that the switch would have a greater impact if I connected it closer to the NUC and indeed, that is what I found. With the switch separated from the NUC by only 0.5 meter of Ethernet cabling, the improvement was quite dramatic. It was like adding a buffered gain stage (ie an active preamp) to an amplifier. Noise floor drops, dynamics improve, sound stage improves and detail clarity improves. The switch before either the SE or the NUC when connected to the network in a standard configuration makes a difference but when the switch is placed in this "direct" pathway, the difference is definitely more stark.
To be honest, the above findings were expected rather than revelations. What was a revelation was how well this switch now isolates the renderer from the server. When I first described the impact of introducing a reclocked switch into the "direct" pathway, I was using only low-noise, high quality servers exclusively. By this time, I had already established that the quality of the server matters and so I never bothered to go back to my noisy Mac Pro with 12-core Xeon. In this instance, with the reclocked switch in the "direct" pathway, I decided to swap out my SE once again and replaced it with my noisy Mac Pro and what I found was truly revelatory. This switch very effectively isolated the noise coming from the Mac Pro. As I A/B'd between SE and Mac Pro, the difference between the 2 was now subtle at best. In blind testing, I was unable to tell that there was a meaningful difference at all.
The significance of this is potentially huge, especially for those interested in DSP or upsampling. Now, with my untreated noisy but powerful Mac Pro, I am able to run RoonServer effortlessly. Even with tens of thousands of tracks in my library, I can search and skim through my library with ease resulting in a much more pleasant and lag-free browsing experience. I can run DSP and probably even upsample to DSD512 if I chose with this beast and with this switch in place, there would be no detriment to SQ! While I haven't tried upsampling to DSD512, I have implemented my version of a "loudness" feature where I have boosted my signal at 100Hz and 10kHz by 7dB so that I can maintain dynamics at low listening levels. While this breaks the "bit-perfect" nature of the stream, I have found this to be a wonderful "can't do without" feature with low volume listening. While this is not CPU intensive, to enable this feature within the NUC results in smooth playback but there is a definite SQ hit in terms of an edginess. With this feature enabled on my Mac Pro and with my NUC freed from any unnecessary side processes, I feel for the very first time that I have a true "no compromise" setup.
Which Switch Is Best?
Despite Adrian's talk about his "super server," he was still months away from having a unit available for me to listen to although earlier this year, he asked if he could ship me one of his OCXO network switches to evaluate. I was already quite happy with the switch that SOtM modified for me that was being clocked by my REF10 and was being powered by my SR7 but I eventually agreed to have him send me one. I know there has been some snickering about the "lowly" specs of the OCXO that Adrian chose for this switch. According to Adrian, it was important for him to find an OCXO that fit inside the chassis of their switch and so he realized that performance specs had to be compromised for the sake of small size although it was his contention that placing an OCXO directly onto the board would have its own advantages and as far as he is aware, his switch is the only switch currently in production that incorporates an OCXO within the switch chassis. While he also tested lesser expensive clocks from Crystek, he preferred the sound he got from this mil-spec clock produced here in the U.S. by Conner-Winfield. Like the switch modified for me by SOtM, the TLS switch also incorporates improved regulators and capacitors. For his introductory price of $650, his switch also includes a custom 5V/2A linear PSU that was designed specifically for this switch.
Once again, say what you will about the pedestrian specs of the clock used in this switch and I realize there are the "engineer types" on CA who believe they already know how something is going to sound even "before the needle hits the groove" based purely on specs but this switch soundly outperforms my SOtM-modified switch even when clocked by my REF10. Obviously, there's more to a component than just the clock and Adrian has voiced this switch beautifully with all that he has done to it. If this switch has one downside compared against my SOtM-modified switch, there is a touch of brightness/harshness with the TLS switch that is not present with the SOtM-modified switch, especially when combined with the REF10. If there is one thing the REF10 does so well, it is the removal of harshness, however, with the TLS switch powered by my SR7, soundstage is bigger, dynamic contrasts are more robust, and detail clarity is improved. When combined with TLS's heavily shielded CAT7 cable (<$200 for 1.5m length), much of this brightness is nicely ameliorated although as good as his CAT7 cable is, I find SOtM's more robustly shielded and filtered dCBL-CAT7 cable to still be better. No matter how good the switch, the quality of the Ethernet cable still seems to matter.
A few weeks ago, May asked me if I wanted to try SOtM's soon-to-be-released sNH-10G network switch. Of course, I said "yes" and here is what their switch looks like:
Their switch (on the bottom) is quite monstrous in size compared to the other switches I have on hand. The switch directly on top of the SOtM switch is the TLS switch. On top of that is my "John Swenson" suggested switch with ground tweak and directly on top of that is the SOtM-modified switch that has been my reference for the past year. At the very top of the heap is my ZyXel Paul Pang TCXO switch that started it all. I would say that the Paul Pang switch and the John Swenson recommended switch with ground tweak work well but result in the smallest benefits. On a scale of 1-10 (where 1 is the smallest improvement and 10 is best), I would assign both of these units a score of 1. My original SOtM-modified switch when connected to the REF10 scores a 5. The TLS switch scores a 7. That means the new SOtM switch scores a 10.
This switch is completely of Lee's design and incorporates an sCLK-EX board. The isolation used is based on Lee's iSO-LAN6 technology. The unit I have is a prototype and so not all of the ports are functional but when connected to the REF10, I would call this switch Lee's best work yet and it is a masterpiece product. It performs roughly on par with the tX-USBultra but considering this switch is placed before my NUC while the tX-USBultra is directly connected to my DAC, this level of impact is remarkable. The fact that this switch allows me to connect my NUC to a noisy Mac Pro and result in the best SQ I have heard in my system makes it a game changer and a more valuable piece than my tX-USBultra. Are these switches sensitive to the PSU that feeds it? Despite all the regulation built into this switch and the TLS switch, the answer is absolutely and emphatically yes. As rare and valuable as my SR7 rails are, I tend to reserve them only for the products that truly benefit and these switches are as deserving of an SR7 rail as any component that I have.
I am aware of the AQVOX SE switch which is no doubt a contender although I have not yet had the opportunity to compare that switch. Of course, we're all waiting for Uptone's new switch. As network switches are right in John's wheelhouse, no one will be surprised if this switch rises to the top, especially if value is taken into consideration, however, for now, SOtM's new sNH-10G when combined with the REF10 has set the bar for the very best switch I have experienced in my system with the TLS switch setting the bar for best value.