Settings for D-Star audio ?

Well the ThumbDV and a Flex 6300 actually works for D-Star .  I heard 6 stations on HF today and worked one station on 17 meters. That station reported my audio as "good" but I am wondering are there any things that we need to too to have good audio when using D-Star?  Any of the TX EQ capabilities need to be invoke for this mode . ?  It seemed odd just transmitting with a stock setting. By the way, this was my first voice QSO with the 6300 , I have not tried regular SSB phone yet. 

I do have experience with HF digital voice from several years ago using the codecs that Peter G3PLX was experimenting with. .  I can tell you that the audio quality with the ThumbDV and a Flex using D-Star was much superior.

Andy K3UK