Dahdi Override rfc2833 dtmf volume?

I have a piece of equipment that trunked with my asterisk box via sip, and uses the asterisk dahdi PRI card for inbound/outbound calls. When dtmf digits are pressed, sip rfc2833 packets are sent. The equipment I have connected sets the volume in the packet to 4, and I cannot adjust that. Asterisk or dahdi when generating those tones for the PRI makes them way too loud and they are clipping and distorting. I had to set the txgain for dahdi to like -6 in order to get the dtmf to work, but now the audio is very low and faxing from asterisk is poor. Is there a way to have asterisk/dahdi forced or overridden to lower the generated tones, or ignore the volume field in the rfc2833 packets and set them to a fixed level so I can increase the gain? If I use SendDigits they are ok in volume so its just digits coming from this equipment that has the volume set to 4. I have no trouble modifying the source and re-building if someone can point me in the right direction of where the code for playing digits on the PRI may be. Thanks! - Jeremy