4 8 or 16 ohms.

https://www.stereophile.com/content/bampw-matrix-800-loudspeaker-specifications

 

B&W Matrix 800 loudspeaker Specifications

 

 

 

Sidebar 1: Specifications

Description: Three-way, reflex-loaded loudspeaker with line-level bass equalizer. Drive-units: two 12" polymer-cone bass, two 5" Kevlar-cone midrange, one 1.25" ferrofluid-cooled, metal-dome tweeter. Frequency response: 23Hz–20kHz, ±2dB free-field. Impedance: 4 ohms nominal (3 ohms minimum). Sensitivity: 93dB for 2.83V at 1m. Recommended power: 150W–800W.

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Use the 4 OHM tap.

Your friend is correct in the sense that it will not hurt the amp or speakers if you try/uuse the 8 or 16 ohm taps.

However, the frequency response of the crossover will be slightly altered from the factory’s intended response.

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https://guitar.com/features/opinion-analysis/what-is-impedance-guitar-amplifier/

https://forum.audiogon.com/discussions/trying-different-output-impedance-taps-with-tube-amps

https://forum.audiogon.com/discussions/any-experience-using-8-ohm-taps-for-16-ohm-speakers

https://forum.audiogon.com/discussions/16-ohm-speakers-any-amp-sounds-better-with-more-resolution-speaker-ca

 

 

@hoosierinohio   Ah ok. I see that the impedance is 4 ohms. Is that what u are referring to ?  So I would need to hook them up to 4. Ohms for maximum performance. 

Holy smokes! Yer gonna crack the foundation with that system!

 

 

@rodman99999   Ty Rodman. I definitely will !! 👍

@elliottbnewcombjr Thank you Elliott. I appreciate it. 👍