Audible Illusions modulus 3A, what would be the next level of up grade?

I agree with kdude66. Going to the Double Impacts from the Pendragons would be a very good upgrade if you like the Tekton sound. I also had Audible Illusions preamps for many years--owned the 2D for 18 years followed by the 3A w/gold phono boards for 6 years. The phono section was tough to replace. I bought a TRL DUDE used on Audio Circle and it has been a sincere upgrade--potent powerful bass, wonderful live mids and uppers, with very live sound overall. It took several tries to find a phono pre I liked as well. I finally bought a used Whest 3.0 RDT SE for $2300, but the phono section on the AI was VERY tough to beat, even with the awesome DUDE doing the line stage. The AI 3A does not eat tubes if you buy AI’s premium matched tubed set. I had the same tubes for all 6 years--changed them right when I bought it used on Agon.

The best part of any Audible Illusions preamp is their phono section, especially the John Curl MC one.  I was upgrading to a better speaker long ago when I first bought the 2D.  After hearing what I could getting sound improvement from over doubling the cost of $900 speakers back in 1990, I kept hearing such a great difference in the sound with any of their speakers vs. my own setup.  I had a good PS Audio preamp with phono then and brought it back in to Quintessence Audio to listen to it vs. the AI 2D.  The AI just brought the music to life and was very organic and beautiful sounding with every record I played--so much so that I bought the 2D for $800 and had a very significant improvement to my system for a whole lot less than buying the better sounding speakers.   The 3A was just as impressive when I bought it later.