Hello. I am installing a new HU to replace the factory radio. I have the two antennae but neither of them fit in the rear of the the HU. It is the BOSS 616UAB unit. I am searching for the adaptor that can mate the old antenna with the new HU. Hoping to get some direction for the experts on here! thank you

 

You will have two antenna wires, one thick and one thin. You can take apart the end of the thick wire to reveal a plug on the end should fit the Boss. I just installed a Boss with a 9” touch screen.

 

ok! I managed to get the antenna hooked up. No modifications needed. Now i have the HU working but it isn’t very loud! It might be something to do with the OEM amp.

 

Could be if you are wanting to use the stock amp. Not sure what harness you got but there is a wire for to enable the stock amp. In my Boss HU I had to disable the internal amp to clear up static and hissing noises.

 

The enable wire for the stock amp makes it turn on and off. Since OP has sound, it works. In order to correctly install a new head unit with the stock amp, you have to use differential outputs (8-pin connector, not the RCA outputs with adapters). If he used the RCA outputs, it would explain the low volume. If he used the 8-pin connector, the HU should supply a sufficiently strong signal for the stock amp. I don't know if there is an adjustment option for this in this specific HU.