It would be interesting to compare the Burson Audio Buffer with the Musical Fidelity X-10 V3 Tube Buffer (sadly out of production though available on the used market) and the Decware ZBOX - Zen Triode Output Stage.
As it turns out, I do happen to have a Musical Fidelity X-10 V3 tube buffer at home. Though my review schedule is full-to-overflowing, I may be able carve out some time and hook up the X-10 V3 to see how it compares. Stay tuned.
Best, Chris Martens
Editor, Avguide.com/Playback/The Perfect Vision
For conventional unbalanced analog audio connections it is desirable that the output impedance of the source device be low relative to the input impedance of the target device. A ratio of 10:1 is normally adequate, or 20:1 if you want to be conservative or have very long cable runs. About the only time this is ever an issue is when someone is using a "passive preamplifier," which basically just sticks a volume-control pot between the source and the amplifier. In fact, the primary function of a properly designed high-level preamplifier stage is to do exactly what the AB-160 is said to do -- provide a high input impedance to attached sources and a low output impedance to attached amplifiers. The high-level stage's gain is also a benefit in some instances, though more often than not the volume will be at a setting where the preamp actually is attenuating the input signal rather than boosting it. So if the AB-160 is really making your system sound better, you've got a serious problem somewhere else!
so the buffer will change the output impedance of my dvd player (600ohms) to that of my passive pre,improving sound plus adding much needed gain for pre?
or does the passive have no impedance?