I am an unfortunate owner of a ROG Theta 7.1 and I have the same problem as you.
Has Asus ever done anything to correct the problem of low sound and positioning?
The Crate software is impossible to use and even has an uninstall application to download ... you should expect that it will bring problems for sure.
I have the Armory 2 FW 0034 as recommended here, but even so for headphones for about 300 Euros we are very bad about the sound quality and 7.1 positioning.
I await news
Generally, surround channels do not have a strong presence unless intended - you're not suppose to hear those channels all the time. Those with a full home theatre will be accustomed to this when watching blockbuster movies. Firmware 0034 simulates that experience more than 0038 and 0039.
Some gamers who buy the Theta 7.1 may try them on and expect surround sound channels to be loud all the time and complain about the lack of surround effects. Firmware 0038 and 0039 lower the volume of the front channels for more presence in the surround channels, so the Theta is tuned to be a better gaming headset that appeals to more people. Of course, all this depends on the content and game you're playing.
These two versions are tuned more for games rather than movies. I have tested version 0039 personally and can honestly say they are very loud at max volume (0039 is slightly louder than 0038). If you really want to, you can still revert to 0034.
Link for 0034:
Out of curiosity, what kind of content or games do you find the sound too soft??
Per aumentare il volume istallate equalizer apo ed aumentare l'aplificazione