[sdiy] speaker to line out conversion

[Video Synth]

Synth-DIYers,

Is there an easy way to convert an 8-ohm speaker to a line-level
output?  I've got some beeping toys that I'd like to interface to my
DIY synth stuff, so I'd like to remove the 8-ohm speakers and install
a line-level output jack that can connect into a mixer, or better yet,
into my modular synth gear.

I imagine that the impedances are wrong to simple remove the speaker
and solder the wires to a 1/4" jack.  Is there a simple/standard
interface circuit that you suggest?

Thanks.

Video.