AC adapters are rated for an input voltage and output voltage. Match the input voltage to your area (i.e. 220V), and the output voltage to the pedal. As long as the input voltage matches, you will always get the rated output (i.e., if it’s rated for a 220VAC input and 18VDC output, don’t give it 120VAC).

In other words, you don’t necessarily need an EHX brand adapter. But you do need to be careful to match the output and plug specs.

Here are the guidelines regardless of what you go with:

1) Make sure you match the barrel plug size. I’m not sure what the Flanger Hoax uses, but I’m guessing it’s a 2.5mm? Tends to be the popular choice on the larger pedals, but I could be wrong for the Hoax.

2) Make sure you match the polarity.

3) Make sure the adapter you use puts out 18VDC. I’d suggest hunting down a local equivalent to the UK adapter you’ve got. Again, don’t worry about the brand too much as long as the specs match.

4) Make sure it puts out REGULATED DC. A lot of third-party adapters not designed specifically for pedals aren’t regulated. There are some old pedals which ran off of non-regulated adapters, but 99% of modern pedals demand a regulated supply, or you’ll have problems.

5) Make sure it puts out at least what the pedal requires. Unfortunately, EHX isn’t knowing for publishing their pedal current usage specs… so I’d advise getting an adapter which is rated for the same amount of current or more.