Isolating PSU outputs

I have a small pedal setup (Multi FX and looper) and going to either headphone amp or mini Katana for practice duty. The multi FX seems to put a lot of junk on the line though and I get a lot of amp hum when I power them from 9VDC supplies, quiet under battery power.

I have a good quality 9V SMPS I'd like to use when I setup a mini pedal board but, would there be a way to isolate the lines from a single SMPS out? Any other opinions/advice on my options?
I'll probably want about 4-5 outputs in the end.