Audible Illusions Modulus 3a and 6kn8?

I know it's not on the "approved" list and the website has not been touched since this company moved from CA to FL. However, it is time for a new tube complement and I do have some recollection of a rave review with these tubes in the phono section. My unit is out of warranty so not an issue, however I don't want to foul the works with undue stress at the component level. Anyone have experience postive or otherwise with this tube set and the this pre-amp? My understanding is this valve was developed by or for NASA. Phil Lesh would be pleased....