They do have MARCS talkgroups and MARCS radios. Chances are if you are not hearing any traffic on the actual Delphos channels, They are just using Allen Counties Channels. The PD would be on SO-02 dispatch and the fire would probably be on 02 Fire East. Bluffton likewise also uses 02 sheriff's dispatch for their PD. I don't know of any of their specific unit identification numbers as I don't usually listen to ACSO, since I am in Hancock but if you know someone or you yourself live there, you can tell if they are doing a traffic stop or something and addresses that you know come up... I will look into it though and see if I can dig up more info .
Delphos PD and FD each have their own TGs and, as far as I know, they are not using Allen County TGs. Delphos straddles the Allen/Van Wert county line so they may be waiting for Van Wert County to move to MARCS so that they have the ability to communicate with all surrounding agencies without maintaining various radio systems.
MARCS is another expense for local budgets. That said, I did hear Van Wert EMA talking to a Delphos PD unit on the DPD's MARCS talkgroup during a severe thunderstorm warning Monday night. I also heard some traffic on the DFD's MARCS channel during a big fire at an insulation company last month.