Another way to do it is put a
8 ohm rheostat
parallel with a 1.5 ohm resistor, adjustable to any resistance from 1.26 to 0 ohm.
https://www.parts-express.com/cat/speaker-l-pads/306
https://www.parts-express.com/cat/audio-grade-non-inductive-resistors/301?N=19850+4294967118+4294962...
https://www.parts-express.com/cat/speaker-l-pads/306
https://www.parts-express.com/cat/audio-grade-non-inductive-resistors/301?N=19850+4294967118+4294962...