Video conferencing tool that offers screen sharing with HQ audio?

[Egyo]

Hey,
We are running a Moodle-based system, and our intent is to have some virtual classrooms (15-20 participants), and one presenter that can share his/her screen and audio. We did run some tests using a whole bunch of different solutions like BigBlueButton, Gotomeeting, Zoom.us, Google hangouts, and others. The only engine that held a satisfying standard for audio was Google's Hangouts on Air (with "studio mode" enabled). The rest, even with good video performance, were complete rubbish in terms of audio quality.
I've been searching for weeks and can't seem to find an engine that suits our needs.

Bonus:
-Moodle LTI integration
-Recording capabilities
-Remote control
-Annotations
-Chat
Any help would be appreciated.
Thanks in advance,
Egyo