I've been around for a much shorter time (23 yrs) than most of the users that have posted here already (except for the 15 year old), so most of my list will be decidedly "low-fi" --- let's see--
1) Unknown brand shelf system from way back (before CD's). Had the little slider bars to adust the EQ, and didn't play anything under 140hz or so.
2)Panasonic 50w x2 shelf system. It's still in the family, but I would never touch it now.
3) Altec Lansing PC 2.1 system. It sounded really good to me, as all I'd ever heard home theater wise at this point was my parents' Bose Accoustimass 10 system
(which they still use). It lives with my parents' computer now.
4) Klipsch Promedia Ultra 5.1 system - my first surround set-up - sounded really good for the price, but was hampered by a very bad quality Creative Decoder designed for use with PC speakers. Sub amp started to slowly die around the end of 2006. Maybe I'll salvage the 8" drivers for an ultra cheap DIY sub in the future?
*uses Sony MDR-XD400 headphones to fill in gap* <--not audiophile quality necessarily, but the best sounding "speakers" I have ever owned
5) (To be completed this week, hopefully) First *real* system!
-Denon 2307CI; Onix x-ls x4, x-cs center; HSU VTF 2.3.
onix's are due to arrive this week
- the very bright klipsch system sats are filling in until then. I'll (hopefully) eventually be going 7.1 if I can find another used satin-black x-ls pair