Experienced with Audible Illusions preamps
Proud owner of an L-2 for the last 5 years or so.
IN te last 3 years i ended up talking to a local tube tweaker/guru that has worked in A.I preamps for years and simply works good magic on them so naturally I had mine modded.
1st off plate voltage plates on the tubes went form a tube killing 135 volts to a very polite and benign 89 Volts, so the choice of tubes now became a non issue now I use SIemems and Amperex 6922's 7308's and E88CC's without hesitation.
THe sound became as a product of further mods, extremely intimate and imaging absolutely wonderful bass went deeper and tighter, top end became absoutely pristine and there.
The mids is where all things changed, became real fleshed out and the detail simply amazing.
THe A.I preamps are very nice indeed to start with but once modded is a real giant killer.
The kicker, you don't have to scope the used market for them as they very rarely come out for sale, people really love them, you can afford to buy your new preamp listen to it and a while then get it modded when you're ready to go the next few steps in audio nirvana, well worth it.
Simply amazing, just wated to share my experience and see if anybody had any other experience to share or improve upon for the love of music.
Almost forgot, best tweak for the tubes are the MCMaster Carr catalog teflon encased silicone rings (2 per tube will make things quieter tighter and better image.)just put the work on measuring the tube and order according to measure.
Here are some popular measures I found :
9319K99 # 135 for 6550 Tubes (Fat part)
# 128 for top 6550 bottle (Neck part)
9319K99 #122 or 121 for 6SN7
9319K26 #116 for 12AX7, 5751, 12AU7, and 6922 tubes, etc. etc.
For the A.I I like the Siemens E88CC with their colorful mids and top end they sound lively and very exciting without getting fatiguing or overly done,but the Amperex 7308 white labels (1950's) really get he bass right with ooddles of detail and the top end that is real.
Imaging once modded gets 5 stars from me.
hope this helps, please feel free to share your thoughts or experiences. make this community a rich place to live and listen.