I think my starting point was as a student in mid to late 1980s in Belfast where I bought a starter system from Lyric Hi-Fi - Rega Planar 2 (I don't think I could stretch to a 3); Creek 4040; Heybrook HB2. Without a doubt the single biggest WOW moment I have enjoyed was changing the Rega over to a new LP12 with second hand Ittok arm and K9 cartridge. The difference was incredible.
My next WOW was more subtle - swapping the Creek out for a Nait 2 - there were alternative amps at the time which seemed to have more sparkle, but the little Nait just seemed such a perfect match for the LP12. It didn't play particularly loud, but within its power limits, it was just great. I still have it.
An Arcam Alpha 8 (still resides in my bedroom stereo with the Nait!) was my first cd player and my next major WOW came with the introduction of a CDS3 - I was overjoyed at the similarity in presentation it had with the LP12.
My further journey into Naim was a disappointment - I bought a 102/180 pairing which, whilst more powerful, never really did it for me. The importance of proper auditioning was established. the 102/180 did offer me a major WOW when I traded them in for a 252/300, a pre/power combo with a sensational synergy.
Final WOW I would like to report was a DIN-DNI Hi-Line for the CDS3 - the improvement made a major impression on me.
Loads of changes have followed over the years, but these were the changes which really grabbed hold and made me say WOW!!