3.1 vs 2.1

[Lindahl]

How much of a difference is 3.1 versus 2.1, considering the pretty clear and neutral speakers (Ascend 170SEs), in a bedroom environment (16x13), where I have complete flexibility of placement across the front? Approx. 9-10 feet from speakers.

I'm wondering if I should add a center (HTM200) to make the dialog more clear (comparable to 5.1). Or is the center speaker really only for imaging? If so, considering that I have complete flexibility for lateral front placement, would this be only a minor incremental improvement?

I'll have a dedicated theater downstairs with a 7.1 setup for when I want the full experience. However, I will be watching 5.1 OTA HDTV and some movies now and then in the bedroom. Usage would be 10% / 40% / 50% for movies / HDTV / music. Lets say 20% of HDTV would be 5.1 - with possibly using PLIIx during stereo to shift some of the sound into the center.

I do plan on testing it out myself, but wanted to get others' opinions as well (I have not placed my order yet, pending my relocation to another city).

NOTE: I may upgrade the center to a 340 or 170 at a much later point in time, so, in addition, opinions on this too would be nice.

[Quinn]

The dialog will be just as clear in 2.1. I played with phantom center this past week thinking I could sell the center to upgrade the R/L to SEs. In my room you can't sit outside the mains. Anyway for me I found I like the way the center channel ties the dialog to the emanating from the display. Phantom mode left the dialog to diffuse from the display for my personal taste. You can use a 170 as a center channel.