Multiple instances of IAXRPT

by second question, I mean
usually for the hub (server) we give radio interface as “radioless” i.e dahdi/psuedo
what if I give it usbradio interface and connect by basestation to it through DMK URI?
ALSO, my multiple accounts of IAXRPT connected to the same server in iax.conf?
few months back you suggested me this link

what if, I remove the raspberry pi part and connect usbradio to the server directly?