Planescape: Torment is a rare game that managed to get me completely sucked into the world.
Fallout 1 and 2 are also brilliant.
I never played Baldur's Gate 1 or 2, but I hope to when I have some free time (free time )
I've heard them with an M^3 configured very close to my old one, still had that upper midrange harshness that made them sound like crap.
The M^3 is a great amp, I doubt it was under driving them.
System Shock 1 and 2 were amazing as well.
The last time I tried to play Deus Ex on Windows XP it felt like I was in in perma-turbo mode and I wasn't able to fix it with the latest patch
Deus Ex Invisible War is terrible \
You don't even need to spend $300 on a balanced cable. You can reterminate the HD650 stock cable (which in my opinion is very good).
For what it is worth I preferred the stock cable to a Cardas cable.