Pass Labs ALEPH 5 vs ALEPH 2

I used to have Aleph 0 (75 WPC, 3 gain stages). Now, I own both Aleph 2 and X-600. They are all excellent power amps.

Some facts:
Aleph 0: 75WPC, mono blocks, 3 gain stages.
Alpeh 5: 60WPC, stereo
Aleph 2: 100WPC, mono blocks, power consumption 300 watts for each (600 total). One transformer for each.
Aleph 4: 100WPC, stereo, power consumption 500 watts. One bigger transformer (I believe) for both channels.

Not sure why Pass Labs will release Aleph 4 after Aleph 2, since they are both 100 WPC, the same design and same grade of parts and I don't know which model is better. Maybe just to reduce some cost without sacrificing the sonic performance for marketing purpose.

Thanks for all of the responses, I apologize for the confusion I caused, I originally meant to seek a comparison between the ALEPH 4 at 100 watts and ALEPH 2 also at 100 watts as Jshaw1004 alludes too. I am still not sure if I appredciate the difference.

Each outputs 100w into 8 ohm but 200w into 4 ohm for aleph 2 only. I believe aleph 2's have higher bias current and damping factor because separate transformer and separate enclosure for better heat dissipation.

Isn't the Aleph 2 160w into 4 ohms? (Not quite doubling down)

You're patly right, that's what was shown in service manual but doubling down shown in my owner's manual. Based on its circuit, more likely 200w for 4 ohms. If fact Aleph amp is so good that I'm going to diy myself after the parts and enclosure arrives.
OTOH, rule number one, you need the speakers on the efficient side in order to appreciate how good Aleph is because its full-time class A and single-end/2-stage design.