Total posts : 45366
1. IMHO, “punchy” bass is more a product of the audio system on the receive end, which is what the Behringer EX1200 is designed for.
2. I think at least some Part 15 transmitters have basic “tone” controls to allow you to change the relative levels of bass and treble. If you need finer control, perhaps a multiband audio equalizer? I would experiment with these before buying what seems to be a very specialized component.
3. Another question – does your transmitter filter the incoming audio? I’m not sure on FM transmitters, but AM boxes may roll off the low end of the audio input (the high end is rolled off to meet the signal bandwidth limit). That would defeat some of the purpose of the EX1200.
Sorry, not much advice, but maybe something to think about?