What growth channel for our games technology job newsletter should we try next?

At www.SeriousGamesJobs.com, we deliver a weekly email containing job openings beyond entertainment relevant to people with game development skills.

Our weekly newsletter contains a diverse range of career inspiration including positions in educational games, AR & VR, and firms using technologies like Unity and Unreal Engine for real-time filmmaking, Machine Learning and AI. Our readers work (or want to work) across many disciplines (artists, programmers, designers etc) and come from all over the world.

To find interested subscribers and grow our reader list, we've previously used paid advertising (Reddit has been fantastic, Linkedin & Google ads not so much) and attempts at SEO optimisation. We've achieved modest success, but I'm keen to see if we can get better return on time & investment.

This month, I'm looking to experiment with another growth channel. I know that there's real appetite from readers of a number of game technology subreddits (e.g. r/UnrealEngine and r/Unity3D, but I'm wary of falling afoul of self-promotion rules across Reddit and other social channels in general. I'm curious to investigate whether there's another paid channel which might be worth a try (podcast ads? Spotify??), or whether submitting to directories or other resource lists might be a good idea.

Indie hackers, I ask for your wisdom- what should we try next? Have you walked the social channel promotion tightrope before, and how did it work?