home entertainment 2007

the file can be played in only one room
at a time. (The Sonos system allows
several players to play simultaneously.)
The DRM-wrapped FairPlay AAC
files downloaded from Apple’s iTunes
Store will not play, however.
Installing the SoundBridge
I initially installed the SoundBridge
M1001 on my office desk, next to the
laptop that serves as my music server.
The SoundBridge has no physical user
markers and all between –92dB and –95dB. I have no
idea what these might be due to—they are certainly not
jitter-related.
I did some Googling online to see if anyone had noted
anything similar. I didn’t find any such comments, but
what I did find was some discussion on the Roku Web
forum (http://forums.rokulabs.com) about the fact that
the SoundBridge converts the sample rate of incoming
data to 48kHz before presenting it to the internal DAC and
the S/PDIF digital output. I checked the X-24K’s samplerate
indicator when it was supposedly being fed 44.1kHzsampled,
CD-derived data by the SoundBridge: “48kHz”!
A Roku spokesperson on the Web forum stated that
though this design decision “makes passing 44.1kHz
sources through untouched impossible . . . we’ve used a
very high quality sample-scaling routine in an effort to
make the resampling as good as possible and it should be
inaudible.” Yes, the SoundBridge does use Analog Devices’
respected Blackfin DSP chip, but my experience has been
that converting data with a sampling rate of 44.1kHz to
one with a 48kHz rate is difficult to do with sufficient precision.
It looks as if the Roku’s automatic but, in my opinion,
unnecessary conversion to 48kHz compromises the
audio data’s noise floor by introducing mathematical artifacts
that I would be surprised wouldn’t be audible. Add
that corruption of its digital output to its underperforming
DAC and analog circuitry, and you can see why I was disappointed
by the Roku SoundBridge M1001. It actually
Fig.8 Roku SoundBridge M1001, HF intermodulation spectrum, 19+20kHz
at 0dBFS peak into 8k ohms, volume control at “100%” (linear
frequency scale).
ROKU SOUNDBRIDGE M1001
controls—it must be operated from its
remote or from a computer via a WiFi or
Ethernet connection. Setup was easy, and
as I browsed my music library on my laptop,
the SoundBridge displayed all of the
album and song titles and artist names of
music I’d ripped from my favorite CDs
using Windows Media Player software.
Then, trouble: I’d visited www.nap
ster.com to buy October’s “Recording
of the Month,” Keith Jarrett’s The
Carnegie Hall Concert (ECM 1989/90).
Once I’d entered my credit-card information,
Napster had rapidly downloaded
the 13 files that make up the
two-CD set and written them to my
hard drive as DRM-wrapped, lossless
WMA files. Download completed, I
browsed my music library, found the
album, and clicked on the first track,
Part 1. The SoundBridge displayed
“ACQUIRING LICENSE”; then, its time
display showed that the music was
flowing through the M1001. Just to
measures worse than the DAC in the cheaper Apple Airport
Express WiFi base station (see
www.stereophile.com/computeraudio/505apple), let
alone that in the more expensive Slim Devices Squeezebox
(see www.stereophile.com/mediaservers/207slim).
Very disappointing. —John Atkinson
Fig.9 Roku SoundBridge M1001, high-resolution jitter spectrum of
analog output signal (11.025kHz at –6dBFS, sampled at 44.1kHz
with LSB toggled at 229Hz), 16-bit CD data. Center frequency of
trace, 11.025kHz; frequency range, ±3.5kHz.
Fig.10 Musical Fidelity X-24K, high-resolution jitter spectrum of analog
output signal (11.025kHz at –6dBFS, sampled at 44.1kHz with LSB
toggled at 229Hz), 16-bit CD data sourced from Roku SoundBridge
via TosLink connection. Center frequency of trace, 11.025kHz;
frequency range, ±3.5kHz.
www.Stereophile.com, May 2007 71