I can't seem to find power supplies beyond 1500W. That'll basically power 1 Antminer S9. If I have 4-5, is it possible to buy a power supply to power all of them?
For standard ATX supplies, 1600 watts is the limit because they're all designed to be useable worldwide - which INCLUDES the USA with it's very common 15 amp 110 volt circuits that anything bigger WOULD OVERLOAD.
For server supplies, outside of "specific designs for mainframes" and such, the largest widely available PS I'm aware of is a Delta model that is rated for 2400 CONTINUOUS watts output with 220 volt input.
For perspective, a 30 amp 220 circuit (which is common in data centers, usually on a L6-30 "drop cord" from "tracks" hanging from the roof) is only good for about 6.6 KW INTERMITTANT usage, or a little over 5 KW 24/7 continuous usage - which fits *2* of those Delta supplies comfortably on one circuit.
Keep in mind that the power density of ASIC Cryptocoin mining machines is extremely HIGH compared to almost ALL computer hardware - most file servers and web servers use less than 300 watts in a 1u case, which has MORE cubic inches than a Bitmain S9 or any other similar-form-factor ASIC miner.
It's also why you aren't seeing ANY miners hit wide distribution with a power draw "at the wall" much over 1400 watts.