I had a subjectively profound experience while meditating on LSD. In a sit I reached a highly concentrated state and felt (with multiple senses) vibrations of high frequency - even teeth vibrated. I saw the object of my meditation, then the process of objectification as an object in a loop that was getting tighter and tighter. At some point I transcended and saw what I intuitively called the Source. This is a good visualisation of how it felt: http://alexgrey.com/art/paintings/soul/oversoul/ - I felt my mind merged with the Source. 

Did anyone experience this? What is this place? Is that how stream entry looks like? I want to be able to reach that state without LSD. Is that possible?

Most people describe stream-entry as a non-experience and when returning to experience they experience a release stress at the deepest level possible for a human being. Because desiring neurotransmitters always involves a dose of stress to control and dominate what is desired the target is that nasty part of the brain that lashes out when desires aren't fulfilled.

EDIT:


http://www.dharmaoverground.org/web/guest/discussion/-/message_boards/message/5787155