Well, these Swan's are passive speakers, so you need an amp. The Swans are also designed for stand placement not desktop.
I have not heard either the Kali or 308P, but I own some JBL 306P and the HiVi 2.2a I own are definitely superior speakers, when both are placed on a stand in a medium room. A more direct comparison might be the Polk LSiM 703s mentioned above. In my room the Swans DIY2.2a sounded significantly more accurate. Flatter frequency response, more detail, and better defined bass. Purely subjective. On the other hand, the Polks look gorgeous, they are really beautifully finished. The HiVi 2.2a (which I finished) most certainly do not