It is rated down to 4 ohms, not 2 ohms.

The number of speaker cabs is not important, only the total impedance matters.

A 4 ohm cab or an 8 ohm cab presents exactly that to the amp - 4 or 8 ohms. Two cabs of an impedance, when connected together cuts the total in half. Two 8 ohm speakers in parallel makes a 4 ohm total. Two 4 ohm speakers makes a 2 ohm total.

item 37 in the manual states a 4 ohm lowest impedance on each channel. it even spells it out with examples of two 8 ohm speakers or four 16 ohm speakers. Both those combinations make 4 ohms.

Each channel has two jacks. The manual explains they are parallel wired. That means the two jacks for a channel are wired together. Just like the two outlets on a wall outlet for AC power. Just like a wall outlet, if ther is a 30 amp circuit breaker behind it, you can plug a 30 amp load into either outlet, but not a 30 amp load into each outlet. That would make a 60 amp load.

So if that is your confusion, you can plug two 8 ohm cabs into the two jacks of one channel, for a 4 ohm load on the amp. NOT a 4 ohm into each jack. Remember, it is the CHANNEL that has a 4 ohm limit, not each jack.

Daisy chaining speakers is still parallel wiring. That means running a speaker cord from the amp to one speaker, and another cord from that speaker to a second speaker, is exactly the same to the amp as running a cord from each jack of a channel to each speaker directly.