Oh I did have a crystal radio under my bed in my elementary school days. But later graduated to the big time with TUBES! LOL
Masters are out for delivery today. Still wish we had a filter description. That said elsewhere folks are concluding that the shipped installed reds are the "new golds" that Bob preferred on the Master 4 https://tinyurl.com/k3zlnph
All I know is I'm using the default filters for my Phantom Sabres (from the recent clearance sale) which, oddly enough are silver and aren't even listed on the Sabre Filter Color Listing on the Trinity Audio site. However, I find them to sound excellent with a nearly balanced sound that might emphasize the bass slightly...a sound that I very much prefer. I've not even tried the other filters...
So, who knows, I may just stick with what Bob has attached to the Masters already.
Cheers and Happy Listening!
-HK sends