I've been experimenting with my Masters since the day I got them. I thought I had a good seal with L kombis but I was wrong, I switched to the enormous foam tips provided and what a difference in mids. When listening to gold-undampened the mids were brought significantly closer and the highs became peaky and harsh in certain recordings. I went on and re-listened to all the filters and still couldn't find a favorite.
The gold undampened can sound too harsh and peaky in some recordings, but the dampened version glosses over the minute details which are fun to listen to. Silver has too much bass, blue not enough bass, purple too much treble. Green sounds pretty good but feels congested and mids heavy plus misses out on high end detail.
I got pretty annoyed that I can't get a good and secure fit with the kombis where a partial seal makes the gold (undampened) filters sound good, but with foam tips that provide a great and secure seal the filters sound too damn harsh.
Here's where it hit me, take the black dampening foam and stick it inside the gold undampened filters. So I did, and what did it sound like? Kind of like the black filters but with slightly more mids maybe, the lack of sparkle and treble detail left me unimpressed, much like the gold dampened filters.
But this is where I may be onto something. I pulled the black foam dampening out of the green filters and they came alive with clear highs! Sound signature sounds vaguely familiar and may be similar to the gold undampened filters but with bassier body and SLIGHTLY less elevated treble peaks, possibly. Unless the green filters are actually just the gold filters anodized green and stuffed with black foam inserts. It's really hard to tell without graphing.
The black foam insert seems to act somewhere between the 6-7kHz range the most from what I can tell, but I don't have any test tones on my DAC to verify this.
Next I'm going to pull the black-inserts from the red and black filters and see if they resemble the silver and purple filters respectively. My uncalibrated ears can tell only so much, feedback is greatly appreciated from anyone who wants to compare impressions.
Edit:
With longer filters I could possibly go back to L kombi tips, but as it is now the current filters with kombi tips don't sit in far enough and the top of my ear pushes the IEM back out under any movement of my head.
I'm listening on a X5II with E12A on about 40% volume