Receiver Speaker Settings: LARGE or small?

Q: How Should I set the:

• Main speakers - LARGE or SMALL
• Subwoofer - SUBWOOFER or MAIN or BOTH
• Center - LARGE or SMALL

And how should I set the OHM setting on the receiver- 4 ohms or 8 ohms.
Def Tech manual says the Mains and the Center can be set to 4 Ohms or 8 Ohms. Which setting is correct and also will give best sound? Here is my system:

• Yamaha RX-V3000 receiver
  
• Definitive Technology BP2004TL main speakers (using LFE cable)
  
• These speakers have built in subwoofers with 250 watt amp.
  
• Definitive Technology C/L/R 2002 center speaker
  
• Mits 55" rear projection
  
• Sony ES9000S DVD player

A: Set the:

Main Speakers: "Small"
I recommend setting your mains to "Small" on your Receiver since the BP2004TL's have a built in sub. You will increase the dynamic headroom of your receiver amplifiers since they won't be taxed to product bass frequencies lower than 90Hz.

Subwoofer: "Subwoofer"
I recommend setting the Subwoofer output on your Receiver to "Subwoofer". That way the subwoofers in your Speakers will always operate in all modes on your Receiver (IE. 2 Channel, DD/DTS, etc).
Note: Make sure you have the Crossover from the BP2004TL's disabled or set to the highest frequency setting to avoid cascading effects of two series crossovers.

Center Speaker: "Small"
I almost always recommend setting your center speaker to "Small since most Center Channel speakers are not capable of producing bass frequencies below 80Hz with much authority, especially since they are placed off the floor and usually above the TV set.

Also, be sure to set the impedance Selector Switch to: 8 Ohm Setting

Never set the impedance switch of a receiver to 4-ohms!

Note about the 4 ohm setting on the backpanel of the RX-V3000
Selecting the 4 ohm setting significantly limits the rail voltage feed to the power amps and thus reduce dynamics, bass output and damping factor. This switch was put on the Receiver for marketing purposes, and so that it can meet UL approval for heat dissipation when presented a 4 ohm load continuously with minimal to no ventilation. With proper ventilation, this should never be a problem (at least 4 inches above and behind the Receiver). In addition, the Definitive Technology Speakers are very efficient ( > 90dB) and thus are relatively an easy load for the Receivers Amplifiers to drive in the 8 ohm setting. Thus I would have to say setting the Impedance Switch to the "8 Ohm" setting will result in better fidelity for your system.