gqrx has support for portaudio, pulseaudio and gr-audio (GNU Radio). It would be great if these existed as port build potions.
A commit references this bug:
Date: Fri Aug 25 10:13:25 UTC 2017
New revision: 448715
- Update to 2.7
- Add option to select audio backend 
PR: 221627 
Submitted by: Christian Sturm <firstname.lastname@example.org> 
Thanks for you suggestion!
It's been added in version 2.7 of the port.