I can confirm that either 1: that's not true or 2: an "insider permanent" activation fully qualifies as "retail activation" in this case. I have a PC which never saw any retail Windows key, nor any unofficial/pirate activator/loader in it's life. I assembled it from consumer parts (without OEM Windows license) and the first Windows OS it saw was a Win10 preview build. I kept upgrading it in the fast ring up to 10525. I even opted out of the insider program with 10240 for some time before I jumped back today for this 10525 upgrade. It never lost the "permanently activated" status. The only way I would lose it if I lost the installation (format C: and clean install without backup).
I actually wonder how they're going to deliver this "update" once it's ready. What I don't get is why they still need new builds to deliver new features and improvements, why aren't they pushed out like cumulative updates instead? It's doesn't really make much sense these days to download a complete ~ 3GB ESD file and perform kind of a new install just because some components have been updated. It's not like they changed every aspect of the OS that makes it necessary. IMO, they should have stopped at build 10240 and keep that up to date (forever) via cumulative MSU packages that can be slipstreamed via DISM, where each new release supersedes the previous one. Service Packs are dead, so what about Builds?
I don't think they're gonna have people start over with this or any other builds. When you think about it even going to 10 was an 'upgrade' for a lot of people. I certainly hope not--how much time do people have--although it could be good for the computer business. I think you're on the right track with cumulative updates. They'll really just be service packs but they just won't call them that. They've already changed version numbers with the number after 10240, so I don't think they'll hesitate to replace 10240 with different build number as well. Service Packs are indeed dead: Windows 2000: 4 Windows XP: 3 Windows Vista: 2 Windows 7: 1 Windows 8: none Windows 10: ???
you are asking all day and no one answered so probably no one has sound issues. i don't use the insider build, but on the normal windows 10 edition i never had sound issues. so either it's a weird bug (maybe no clean install) at your end or wrong settings or a driver error. try older drivers.
if they were running on 7/8/8.1 they will probably run in windows 10 too. for example i got a VIA HD Audio onboard card. the newest driver provided my windows update (and the only one available for windows 10) does not work probably. you can't enable enhancements like equalizer etc and it sounds like s**t. but when i install a old windows 7 driver, which i used on 8 too, i get the same good sound just like on windows 8. try compaitble mode or something like this. or install it manually in the device manager. good luck