Nordost Valhalla 2 USB 2.0 Cable Review
I've had little use of high-end digital cables until quite recently. A long string of CD Players from Denon, Meridian and several from EMM Labs were all one box affairs – put a silver disc in slot A, take analog balanced output at the other end. When I ultimately moved to an outboard DAC, the EMM Labs DV2, I used the proprietary EMM OptiLink glass cable which provides galvanic isolation (electrical independence) from the source, as does its USB input.
But I was so impressed with the exaSound Delta Server I reviewed recently that I bought one for myself. The DV2 does such a superb job removing jitter on all its inputs that I'm hard-pressed to hear any differences when I connect the XDS1 to the DV2 using OptiLink or AES/EBU connections. And this is a highly resolving system with Nordost Valhalla cables powering and linking the DV2, a Soulution 5100 stereo power amplifier, and YG Hailey 2.2 loudspeakers.
I compared the exaSound Delta Server to the spinning silver discs in my XDS1, both feeding a digital stream into the DV2 in my Delta Server review. If I used a 44.1kHz/16-bit Redbook source (from CD or Delta Server file or Qobuz stream through the Delta, I couldn't tell much difference at all using the two-meter USB cable provided by exaSound. The XDS1 had a little more impact and sounded more relaxing on some discs, while sounded identical on others. But if I switched to comparing a DSD file on the Delta Server against an SACD disc of the same music, differences did emerge more consistently, with the XDS1 having a small advantage.
I wondered if these differences were due to the Delta Server, or were a function of the particular and unbranded USB cable I was using. I tried other USB cables I had in house, and they all sounded significantly worse than the one I had been testing. Images crept back towards the speakers, and the sound was significantly less relaxed. Instruments became less colorful, although the leading edges and the resolution still seemed first-rate.
So, having exhausted my supply of USB cables, I contacted Nordost, whose Valhalla 2 cables I used for power supply, interconnect, and speaker cables. Could they send me a matching Valhalla 2 USB cable to link the Delta Server to the DV2? Our Creative Director, Steven R. Rochlin, suggested we complete the Valhalla 2 loom by connecting the Delta Server to the internet through a matching Ethernet cable. Nordost does not offer a Valhalla 2 Ethernet cable, but they do have a Heimdall 2 Ethernet cable in their Norse 2 range, and they supplied me with a 3M length. This is their best Ethernet cable to date and should be a good match in sound quality, if not in color (it's red, not pearl white). Norse 2 sits between the entry-level Leif range and the reference level Valhalla 2 range of Nordost cables. Above the Valhalla 2 sits the Supreme Reference Odin 2 cables for Power cords, digital and analog interconnects, tonearm, speaker cable, and bi-wire jumpers, but neither USB nor Ethernet cables.
Valhalla 2 USB Cable Construction
Nordost selected a flat twin-axial geometry for this cable rather than the more common twisted pair, allowing the signal wires to run in parallel for maximum transfer speed and the shortest physical path. This separates the positive and negative power legs, isolating them from the signal conductors and from each other. The power conductors are covered in a finely braided silver shield, and the signal conductors are individually shielded similarly. Each shield is connected to the metal-plated backshell of the HOLO:PLUG terminations to avoid EMI, RFI or noise.
Four high purity 19AWG solid core conductors are used for power and signal, each one silver-plated then suspended in the proprietary Dual monofilament technology, which gives each conductor an air dielectric while firmly damping it in place inside the shielding and FEP insulation. Nordost offers only certain mechanically tuned lengths, designed to minimize internal microphonics and high-frequency impedance resonance. The precise cut of each conductor ensures the uniform arrival of all signals, dramatically reducing timing errors.
Nordost design their high quality HOLO:PLUG USB Type A and Type B terminations for this application. They are low mass but fully shielded to ensure perfect signal transfer. These images will show just how serious looking these plugs are compared to regular USB connectors. The two inexpensive generic USB cables have black plastic shells for the connectors.
Heimdall 2 Ethernet Cable Construction
As in the Valhalla 2 USB Cable, Nordost has implemented mechanical tuning here. This process utilizes meticulously calculated lengths, which have been dictated by the geometry, material, and application of the cable, in order to reduce internal microphonics and high-frequency resonance. Again, the precise cut of each conductor ensures the uniform arrival of all signals to minimize timing errors.
This cable can support frequencies of 1000MHz and transmission speeds of up to 40Gbits / second, which is beyond the Cat 7 standard and offers far more bandwidth than is needed for this application. The Heimdall 2 Ethernet Cable is terminated with a completely shielded and ruggedized 8P8C / RJ45 connector designed to further resist EMI and Electro Static Discharge (ESD). If you need a right-angle connector, you can specify which end and direction the connector should point, yet it will cost you an extra $80. As it turns out, there is very little clearance below the exaSound Delta Server so a right-angled connector would save me having to raise it up on stilts.
This image above shows the difference in construction between the Nordost Ethernet connector on the left and the generic cable on the right.
Let's start with the USB cable. I was delighted to find that the Delta Server exactly matched the performance of the XDS1 on both Redbook CD resolution and DSD / SACD, so I have to rate its performance as perfect. You can tell the difference from the exaSound-supplied USB cable readily on AB testing, but it is more apparent when you listen for extended periods. The Valhalla 2 USB cable throws a bigger image that extends way out from the speakers to fill the hole in the middle. Music is simply more lifelike and relaxing to listen to. When you move to higher resolution files, such as 192kHz/24-bit, the sound pulls further ahead of 96kHz/24-bit when you use the Nordost cable, with the image expanding to fill the space, whereas the generic USB cables do not show much further improvement.
For the Ethernet cable comparison, I used three-meter lengths of Heimdall 2 and generic cable. I was able to detect some differences, more so on the 192/24 Qobuz streaming than on lower bit rates 96kHz/24-bit and 44.1kHz/16-bit. These differences were small. Again the biggest difference was in the degree of relaxation the music offered, and the ability to fill out the soundstage. But in my system at least, the improvement from inserting the Heimdall 2 Ethernet cable into the system was much smaller than between USB cables, and I had my work cut out here. When dealing with Qobuz 96kHz/24-bit or 44.1kHz/16-bit streaming or any of the TIDAL streams (with or without MQA), I couldn't tell the difference.
So, I would like to suggest that the exaSound Delta Server is even better than in my earlier review, matching the quality of the digital stream offered by the EMM Labs XDS1 ($25,000), having one of the best CD / SACD transports available, working with its preferred OptiLink connection to the partnering EMM Labs DV2 DAC ($30,000).
To Buy Or Not To Buy
USB cables do seem to make more of a difference, and that difference widens with the bitrate of the source, and I suspect as the length of the cable increases. At this point, we should remember that the DV2 does a superb job of removing jitter from its USB input (indeed from all of its inputs) so if you are using a less capable DAC (almost all other DACs are less capable) then you may note bigger improvements from the Valhalla 2 USB cable. Similarly, if you need a longer length, the choice of cable will be more important, and the same goes for the quality of your source or server.
The exaSound Delta Server is built to deliver the cleanest possible bitstream by using the simplest possible operating system with carefully designed buffering and an over-specified power supply. If you are using your laptop or a more general-purpose computer or a less optimized special-purpose server, the stream you are putting into your USB cable may not be so clean and error-free. A top-notch cable like the Valhalla 2 USB 2.0 may very well be justifiable and recommended.
But these are general remarks and the only way to tell is to try similar tests in your system. Ask for a loaner or an in-store demo. If you can't tell the difference with your ears, then don't bother. If you can, then consider an upgrade, and know that the Valhalla 2 USB worked perfectly for me and is built to last. It is hard to assess the value for money of a component such as this – so much depends on your situation. The Valhalla 2 USB cable has moved my music server source up a notch to match the sound of the superb EMM Labs XDS1 Reference CD/SACD Player, and to improve on it with access to music files of higher resolution than SACD on my server and does the same for Qobuz 24-bit/192kHz streaming. That's worth good money to me.
Most streaming set-ups involve a network switch (which is typically far below the standard of the High-End Audio equipment accompanying it), or a router, which is basically a switch with advanced functions (such as DHCP, Wi-Fi, and firewalls). Just like with "general cables", an Ethernet cable has two goals: Protect the signal from external and internal electrical and mechanical interferences, and give the signal the best, most predictable, and unaffected circumstances to travel through (low capacitance and impedance). However, a cable can only maintain the signal it receives — it can't improve upon it.
When using a switch or a router, you experience the same phenomena, as you do with all Hi-Fi cabling: garbage in - garbage out. Depending on the quality of the switch (and unfortunately there are very few good dedicated audio switches out there), it may introduce timing errors and jitter, allowing for EMI, RFI, and more. Routers will do the same, maybe even to a greater extent because of their additional functionalities.
In our experience, when comparing Ethernet cables, one needs to address the cause of the noise etc, in order to truly hear the impact of the cable. Otherwise there's a big risk that even the best Ethernet cable simply isn't being given a signal of good enough quality to excel the system's performance. Long story short, you have to make sure that you have the best quality switch / router that you can find in order to appreciate the significant differences and sonic improvements that a high quality Ethernet cable can produce.
Nordost Heimdall 2 Ethernet Cable