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On the inside, there is a lot going on under the hood of the silver chassis. The DAC section of the Conductor features a 24bit/192khz Tenor TE8802 USB receiver used in "Asynchronous Transfer Mode." Burson stresses they developed a custom circuit for the Sabre32 chip, and did not co-opt previous circuit designs from earlier products. Burson says, "most manufactures use standardized building blocks when designing an analogue circuit for their DAC chip. These building blocks include IC opamps, IC regulators, standard power supply boards, and off-the-shelf transformers. The very meaning and purpose of such IC building blocks is to simplify the design process. The downside of such an approach is that inevitably many components within each building block are irrelevant to the application."
I have always believed that implementation is just as important as using high quality parts and circuits, and Burson addressed this by saying, "to realize the full potential of the SABRE32, we designed a new FET (Field Effect Transistor) output stage to support its unique sonic characteristics. With only 20 carefully selected and matched components on the signal path, this output stage amplifies every analytical output of the SABRE32 without coloration or loss. Two new low noise power supplies were also developed in combination with a customized transformer. Together they ensure the digital and analogue stages are powered separately with the cleanest power possible."
The preamplifier section is a point of pride with Burson. They stressed it was not just an add-on feature, saying, "we did not simply solder a piece of wire from the headphone output jack to create an unrefined preamp. Instead the preamp output has been extracted from the voltage gain stage before the current gain section, to create a preamp that reflects the full potential of our FET output stage, and our less is more philosophy." As noted, there are selectable output settings -- Low, Medium, and High -- for matching with a power amp. The volume control features an in-house designed 24-stepped attenuator, which uses one < 0.1% metal film resistor in the signal pat. The only thing "missing" from the whole package is remote control capability, but purists will not mind. Another item I would have liked to see is an incoming sample rate indicator.
I will say upfront that the one capability of the Conductor that may get short shrift here in this review is the headphone amp section. Only because I am far from an aficionado, and the only set of cans I own are a modest, but high fidelity, pair of Grado SR60s. Disclaimer aside, I did spend some time listening, and it was among the best I have heard. That being noted, Burson’s reputation among those in the know is beyond reproach, and again careful thought and engineering has gone into the headphone amp.
Burson says, "most headphone amplifiers use standard IC opamps in their designs. Such opamps are very cheap and easy to apply, however they are inferior. This is because they are not tailored for a particular audio circuitry, and they contain many low quality and unnecessary components which degrade audio signals. Three years ago we developed the HA-160 headphone amplifier. Instead of using standard IC opamps on the signal path, we designed tailor made circuitry using high quality discrete components. Because of this, we were able to reduce components on the signal path to optimize its operation."
Conductor In Use
I first set up the Conductor, using its fixed outputs, into a Channel Islands Audio passive preamp, driving an Audio Research VS55 tube amp and Thiel CS2.4 speakers. Cables were Transparent and Stager for analog, and DH Labs for digital. My sources were a HP Laptop running Windows 7/Jriver 18, a Squeezebox Touch, and the recently reviewed Musical Fidelity M1 CDT CD transport. After giving the Conductor a week to settle in, my initial impressions were that it offered up a beautifully spacious sound, with lots of depth, and it was incredibly quick on transients. It became difficult to listen to just a few songs on well recorded albums. I found myself listening all the way through, losing track of time.