Hmm interesting, I'm using a L337 Drone MB with the same ALC 1150 chip on it and my audio sounds great. It looks like your board has a lot of software they use to improve your audio quality so you might investigate that.
Both the ECS Drone and MSI G45 comes with audio improvement, albeit slightly different one. Both are based on ALC 1150, which by itself already better than the old ALC 892 and 898. I think the MSI board also has gold plated contacts.
Hmm I guess I don't have the issues with the alc 1150 you're describing. I use it with an optical cable run through a dolby processor into a turtle beach headset. I do use hacked/unlocked drivers to be able to get a dolby signal through the optical line so maybe that's where the difference is.
Audio Boost is about equal as Asrock's Purity Sound. Those are not just plain ALC 1150, but they also add several improvement and a headphone amp. The G43 don't come with Audio Boost.
I think the ALC 1150 based Asus SupremeFX is better than Audio Boost according to some reviews, and that is not the even better SupremeFX Formula. Only a few LGA 1150 motherboards don't use Realtek chips, like Creative SoundCore on a few Asrock and Gigabyte motherboards.