Nobody was selling $1000 digital cables. The cables UHF used to confirm validity of Nugent's claim awere Atlas' entry-level and top-end digital ables ($93 and $278 for 1m). Our rep didn't believe UHF either so he grabbed the most expensive cables they carried to do a similar comparison, which were from Harmonix. Actually, the 1.5m cable he used sells for $1700. Different cables, different ears, same results.
Nugent goes through some different math so I'm just going to copy the text from the article.
Chris
"There is a short but finite time between the initial rise of the signal voltage and its arrival at full voltage. The receiver circuit, at the front of the converter, must interpret the signal, and “decide” when it will consider that a “1” has arrived. That interpretation presents a potential for an error in timing, unless it is absolutely consistent from one data block to the next. In fact, it may not be. Because neither the circuits nor the connectors nor the wire are perfectly matched for impedence, some of the energy arriving at the converter will actually bounce back toward the transport, from which it will bounce back again. Thus the converter will receive the imperfect square wave, and its echo. Now we have potential for confusion. Here’s Nugent’s take:
When a transition is launched into the
transmission line, it takes a period of time
to propagate or transit to the other end.
This propagation time is somewhat slower
than the speed of light, usually around
2 nanoseconds per foot, but can be longer…
When the transition reaches the end of the
transmission line (in the DAC), a reflection
can occur that propagates back to the driver
in the transport. Small reflections can occur
in even well matched systems. When the
reflection reaches the driver, it can again
be reflected back towards the DAC. This
ping-pong effect can sustain itself for several
bounces depending on the losses in the cable. It
is not unusual to see 3 to 5 of these reflections
before they finally decay away.
So, how does this affect the jitter? When
the first reflection comes back to the DAC,
if the transition already in process at the
receiver has not completed, the reflection
voltage will superimpose itself on the transition
voltage, causing the transition to shift in
time. The DAC will sample the transition
in this time-shifted state and there you have
jitter.
If the rise-time is 25 nanoseconds and the
cable length is 3 feet, then the propagation
time is about 6 nanoseconds. Once the transition
has arrived at the receiver, the reflection
propagates back to the driver (6 nanoseconds)
and then the driver reflects this back to the
receiver (6 nanoseconds) = 12 nanoseconds).
So, as seen at the receiver, 12 nanoseconds
after the 25 nanosecond transition started,
we have a reflection superimposing on the
transition. This is right about the time that
the receiver will try to sample the transition,
right around 0 volts DC. Not good. Now if
the cable had been 1.5 metres, the reflection
would have arrived 18 nanoseconds after
the 25 nanosecond transition started at
the receiver. This is much better because
the receiver has likely already sampled the
transition by this time.