madisound的RAAL产品目录上也写道(http://www.madisound.com/pdf/printcatalog/raal.pdf):For direct coupled tube SE-ribbon, we succesfuly
developed 175:1 ratio, -3dB at 120kHz Amorphous C-core transformers that can carry DC idle current of
SET. Impedance conversion is about 30000:1, bringing the 0.1 Ohm ribbon up to 3kOhm, good for plate
loading of most triodes in HF.