This has been posted on a few other forums but I haven't had a reply yet.
I've got a problem with my Omnia 7. Somehow, plugging in headphones causes the speaker volume to be boosted substantially after the headphones are unplugged, with no change in the actual software volume level. I'm not sure whether this is a software problem or what (it certainly wasn't fixed in Mango, at least). Rebooting the phone is the only way I've been able to fix it (ie, reduce the volume to what it was originally).
I've heard of people complaining about the loudness and lack of volume variation in the Omnia, but I'm not sure if this is linked to that somehow.
If someone can test this out it would be great, if only so I can get my phone replaced if it's specific to my device. Just reboot your phone, and observe the loudness of the lock/unlock sounds before and after headphones are inserted and removed. It doesn't need to be tested on the Omnia 7 specifically, though - if it's a software issue it's likely to be present on other devices as well.
TLDR; all speaker sounds, whether that be from music, games, system sounds, etc, are louder after I use earphones, even if the volume number is the same. Rebooting it fixes it. If anyone with any device could test this it would be a great help.