Not much in carefully controlled listening tests from me, I'm afraid. My Linn LK1 preamp died of a control board fault after about 18 years of service and I replaced it with an Audio by Van Alstine OmegaStar PAT-5 (purchased used directly from AVA). Music was just as enjoyable (LP12/Ittok/LK2/Saras were the other components), which I couldn't say when pressing an NAD 1020B preamp into service when the LK1 was on the fritz.
More recently, I replaced the LK2 poweramp with an AVA Insight 240. System configuration was a bit different, with the LP12 sharing time with a Well Tempered Record Player (Grado cartridge and phono stage) and Vandersteen 1C's replacing the Saras (driver failure; no replacement parts available). Compared to the LK2, the Insight 240 retained what the 1C's were capable of with respect to pitch relationships, rhythmic coherence, and dynamics while adding a bigger, deeper soundstage with better space between instruments and more stable and precise imaging.
More recently, I replaced the LK2 poweramp with an AVA Insight 240. System configuration was a bit different, with the LP12 sharing time with a Well Tempered Record Player (Grado cartridge and phono stage) and Vandersteen 1C's replacing the Saras (driver failure; no replacement parts available). Compared to the LK2, the Insight 240 retained what the 1C's were capable of with respect to pitch relationships, rhythmic coherence, and dynamics while adding a bigger, deeper soundstage with better space between instruments and more stable and precise imaging.