Although not specificacilly specified on the litt, the rated attenuation would be valid for perfectly defined source and load impedances. I can hardly imagine it is for 600/600 matching, since the basic connection would already introduce 6dB attenuation. Seems more likely to be for bridging (low source Z/high load Z). Then, what is low, what is high? 600/15k? or 600/control grid?Aryuserius said:Many thanks for the quick explanation and info. Hopefully I can find a application for it.