I purchased right before M&K closed shop the S-150 THX Ultra "AC" angled center speaker and I recently purchased 3 more off of ebay.
The manual says that the speaker does not support bi-wiring (and the internet seems to poo-poo it anyway) but it suggests that you bi-amp it from an M&K Subwoofer but then doesn't explain how to do this. From internet research it seems that only speakers that have two speaker in's (tweeter and midrange I think) can bi-amp. The S-150's only have 1 speaker input. I have two M&K subwoofers one of which has speaker outs. Do I simply attach both speaker wires to the single speaker input?
A week ago I decided to upgrade my L & R S-125's which lead me to the purchase mentioned above.
I found a reputable seller (he will accept a 30 day return and tons of great reviews) on ebay that was selling L/AC/R S-150 THX Ultras. They were shipped out real fast and are in perfect shape.
My original S-150 has two switches on the back. One for narrow/wide mode and another if you want to run multiple speakers per channel in a "Vertical Stacked" configuration.
The new speakers are missing these switches. The model numbers are the same and nowhere in the manual does it mention that there is a model without these switches. I also can't find any mention of an S-150 without them. One post I read a guy say, "I have the professional version of your speaker" but that's it.
Any idea if these could be fakes or perhaps new ones made by the MK Sound company which bought the designs? (but then why didn't they copy this switch design too)