Baring the known deficiencies, these are wonderful sounding preamps. But you do need to consider the synergy with the rest of your setup, and adjust accordingly.
I have AI Mod3a (with a custom 17 silver faceplate) that Ive grown very fond of. Im using Russian military grade (ultra low noise) tubes with dampeners. (They last for ever.) Im also using an after market Prelude power cord.
All I can say is the sound is phenomenal
very full soundstage, clean highs, and tight lows, with nothing added. My AI has become the center point of a system that I consider to be final.
Im using the following inputs:
Turntable
I use an older VPI Aries with a Rega RB300 arm and incognito wiring, with aVPI SDS. Im in between cartridges at this time
The moving magnet phono section of the AI is very good, although I only have limited experience with other phono preamps. I will admit Ive been startled at times thinking someone was in the room when in fact it the realism of the vinyl.
CDP
Im using a Wadia 830 (modified by GNS), plugged into the tape monitor input. Besides sounding great the Wadias volume control provides the flexibility needed for micro adjustments to the dual volume controls (and high output) of the AI. Additionally the Wadias digital inputs allow me to run the audio from my digital cable box and DVD player (Oppo 970) into the AI.
FM Radio
Remember the days of wireless
. Here too Ive got a unit with a variable output (controlled by the volume knob) to make micro volume adjustments. Plus the McIntosh MR77 (w/mods) sound real sweet.
Misc.
I use a Logitech Wireless Music System to stream from my PC to the preamp. (Music that matters KEXP.com, Thank you Seattle). Ive also got a cradle for the ipod feeding into the mod3a as well.
For amplification Ive got the Mod3a feeding into a McIntosh MC402 (a new classic), which in turn drives Dynaudio Special 25s. (For two channel home theater Ive added Dynaudios Sub250 for that kick you back into your chair feeling.) Also I highly recommend using Discovery interconnects with your AI.
All-in-all, despite all the (well deserved) bad press the company gets, the AI Mod3a is still a great value for the money and can be the cornerstone of a darn good (if not reference) stereo.
Good Luck
Tony