well it gets even more confusing. to try the asio drivers i went into control panel and disabled the onboard sound and then re-enabled the soundblaster. i was listening to the creative sound card through headphones when it worked with the asio driver. so i unplugged the headphones and tried an mp3 and the playback was silent - hence the above post.

but having lunch i remembered that the phones connect to the soundblaster through the front panel but the pc connects to the speakers through a jack lead. and the jack lead was plugged into the onboard sound jack outlet.

so rather than pull out the pc and try the soundblaster socket, i made sure the soundblaster was enabled and listened on headphones. sure enough the mp3 played so i pulled the pc out and reconnected the soundblaster output to the speakers.

it now all works! i had tried the fix Mario mentioned above (admittedly not running the driver in compatibility mode) but there was no sound. all i can think of is that various restarts have installed the driver properly.

and I'm sure Matt will be amazed to find that Soundblaster audigy 2 zs still works in 2020! I did nothing at all other than the original fix Mario mentioned which I had already tried.

so I'm a happy bunny but a puzzled one