OpenAL-soft usually takes < 1 % cpu here. However if combined with decoding multiple opus/vorbis streams, the total is around 5-10%.
So, mere positioning and falloff calculations wouldn't really pay off. On the other hand, if the card had hardware decoding for a huge number of streams, in all popular codecs, and a good amount of local RAM, it would be very useful.
Ship all your sounds to the card's native RAM, in compressed format, then just send the positions and other signals.
But then, no card has vorbis/opus hw decoding nor a good amount of local RAM. Many do have mp3 decoding, but not for many streams at once.