Although these speakers do give a slightly improved sound over the iMac speakers, they are what I should have expected for the price.
They are adequate but do not match the description given for them on the Apple Store website.
The treble is fine but the bass is only fair and frequently distorts depending on the selection of music.....meaning if it is a reasonably new recording with full bass, the speakers will distort the sound.
These speakers are far less than average in performance.
They are disappointing, as I suspected they might be, so it's my own fault for buying them.