I was just fitted with ActiveVent this week with my Audeo P90. They have the Titanium custom earmolds and as MDB stated, they are fully sealed, but when the vent is open it’s just like having vented custom ear-molds. I’ve had a number of custom molds in the past from acrylic to silicon and they have all felt as you describe as full in the ear. The ActiveVent with the titanium ear molds are the first where I can hardly tell I have them in, and definitely not that full feeling. I would even go so far to say I feel them less than a domed tip. I’ve found the overall sound is more natural and the streaming is much more full and clear. They are the smallest, best snug fit ear molds I have ever had. There are some quirks and getting used to a closed vent when streaming or calls, but it’s not much different than using a good quality earbud for calls and streaming, although the streaming sound still isn’t as good as music earbuds. The thing that’s most irritating is when using programs on my phone and iPad where some apps auto play adds or alerts activate the microphone for listening, the vents open and close a lot. I’ve been able to resolve some of those issues, but not all. But overall, so far I’m impressed and glad I switched, but I’ll hold out recommending them until I get more use and see the durability over time.