driver compression test

hi, i have something to ask.
Are the tests and measurements that are done on compression loudspeakers always performed together with a horn or a waveguide? .
if this is the case then the result is the sum of the characteristics of the two elements.
Let's take for example this test:
https://audioxpress.com/article/test-bench-faital-pro-s-new-hf1460-pro-sound-compression-driver-1
The horn used is LTH142. but if I use for example a karlson K-tube, what are the characteristics that change?