I have two Chauvet DMX 35 Dimmer pack (max 7A per ch). I am wanting to buy par64 cans but can it handle it?

I am assuming no cause

7aX120V=840/2=420Watts, which wouldn't be enough would it?

No, it would. Why did you divide by two? You can use 500w or 600w lamps just fine. Though when they blow out, it can take the fuse with the lamp. Not uncommon.

Also be aware that 120v is best case scenario. Worst would be something like 100v or 700w.

I'm not really sure why I did that guess I shouldn't try to do math at night.

anyway today I look at the bottom of the unit and apparently it only allows 550W (max 2200 total) per channel which is fine.

I bought a Par64 today. works fine

Always Remember Watts Divided by Volts Equals Amps.
W/V=A
make sense?
Sincerely,