Bookshelf Speakers?

Used Zu Audio Tone fit the requirements.

Later, as budget allows, you can pair them with a subwoofer.

I remember hearing these paired with a Zu Audio Method subwoofer during a Zu Audio Tour stop in Los Angeles, and thinking the sound was competitive with the original Definitions.

Devore Fidelity Gibbon 3XL (90db/8ohm nominal)

Second the Triangles. Hard to beat.

Second the Triangles. You could also explore some floor standers like Triangle Antal and Celius... 92 db sensitivity and easier to drive than the Cometes.

It'd probably result in more pertinent recommendations if you specified a
budget. The term "downgrading" has a vastly different meaning
depending on one's bank account.

BTW, you can pick up a used pair of Klipsch Forte II loudspeakers for around
$600, and these are full range (down to 32Hz), 99db. They are often available
in the midwest and can be found on Craigslist or EBay.

This is assuming you are changing to bookshelf speakers because you believe
this size is necessary to enable some cost savings. Not necessarily so.

What's the motivation for bookshelf speakers, lower cost or space savings?