How many channels on a factory 540i amp?

Looking at the two big electrolytics in the picture Derek posted HERE I have to wonder if the factory 540i amp is really a 4 channel or two channels with some more over-engineering to emulate 4? Also, does any source show what impedence the factory crossover presents? I bought a 4x50 for the fronts and a 2x200 for the sub, but since the sub is a DVC with a max power rating of 300W, it may work better to use the 4x50 bridged for the sub and the 2x200 for the fronts (if the amp really turns out to be only 2 channels). All at 4 ohms, but both amps are old 90's PPIs and both will work fine at 2 ohms (except driving a parallel-wired DVC sub bridged). As a side note, I noted that someone posted that a 15" tall sub box was the biggest the E34 would accomodate. I wish I had seen this before I mounted mine in a 16" tall enclosure two days ago. Guess I had better warm up the saw.

Having had a look at the picture, although there isn't enough information in the picture to settle things one way or the other, it looks as if it's four channel amplifier.

You can see four metal heatsinks. Each of those heatsinks is probably for a respective amplifier integrated circuit (IC), for a total of four ICs and thus four channels.

yep 4 channels and 4 crossovers for 10 speakers.

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Originally Posted by Tiger

yep 4 channels and 4 crossovers for 10 speakers.

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They could even be stereo amps, each of those IC's has just enough pins to be stereo... though that would be a long shot as there'd be no provision for the negative bus input.

Could I wire a replacement amp with each front and back crossover in parallel to present a 2 ohm load (assuming the new speakers are 4 ohm)? I am not sure I want to do this, just looking at options.