My vote is HC5. I have the HC4 and it comes out sounding "pinched" on my K2. If I want the DX sound I can adjust the TX equalization on the K3 using the HC5. But it won't work as well the other way around because the HC4 eliminates lows to start with and the equalizer can't create sounds that the mike didn't pass along. 73 de K1ESE John