A shameless plug for the SP3
I use a pair of SP3 speakers with my home K3S. If you use Elecraft's AFX feature (main receiver alone) or if you’re using both main and sub receivers at the same time, you’ll be amazed, like me, at how expansive the stereo audio space “feels" with speakers this good. It can reduce operating fatigue, help with diversity reception, and take full advantage of broadcast-quality signals.
To make sure we got the SP3’s acoustics right, we collaborated with an expert in the field--literally a professor of audio physics. He helped us select the speaker, specify the cabinet materials, and ensure there were no oddities anywhere in the frequency range. The cabinet is rock-solid, using overlapping segments to eliminate all edge-to-edge joinery. You could just about park a truck on one (well, OK, a small import).
Several SP3 owners have posted comments here:
...so you don’t have to take my word for it.
In addition to its great sound, the SP3 includes a front-panel switch for selecting between two mono or stereo audio sources, e.g. two transceivers.