bombadil....the 340s throw an even bigger soundstage than the already big soundstage the 170s are capable of. That, and reaching into the lower bass-midbass region is probably the two biggest differences I've noticed.

Personally, I don't thing the 340 upgrade is stupid. 2-channel redbook CDs bennefit as well as cohesiveness. As mentioned before, the 170s integrate well with the HSU sub. The 340s are as close to seamless in transitioning to the sub as any other speaker set-up I've heard. It's like the 340s reach down to 20Hz. We know they can't so that seamless integration is quite impressive.

I'm breaking mine in now. So, I expect them to get better sounding.

Was watching Gladiator (for the upteenth time) last night. Even though the 340s are only a little more efficient on paper than the 170s, it made a significant difference to the "big" sound I was looking for.

Sony WE610 60" LCD RPTV
Pioneer Elite 59TXi AVR
Pioneer Elite 59AVi Universal DVD player
CBM 340 Front L/R
CBM 340c Center
HTM 200s Rear L/R and rear surround (6.1)
HSU VTF-3
Monster THX certified interconnects
DIY speaker cable (that's better than anyhing I can purchase elsewhere)