power supply noise - KAOSS pad (4.5v) off 9v gtr pedals

[wax+wire]

Hi

So I'm trying to power a KAOSS Pad Mini (4.5V approx 500mA) off a 9V wall wart that I also run two casio keyboards and a boss power supply. I've used a variety of 9V-to-4.5V circuits : a LM7805 IC, a DC-DC 3A circuit bought for only a few dollars on eBay, and a 12v to 4.5V DC convertor I found inside a cigarette lighter adapter.

Thing is, all of these induce heaps of annoying noise into my signal. There is no noise if the KAOSS pad is run off batteries, no noise if the KAOSS pad (and voltage regulator) is run off of a separate 9v/12v transformer through the regulators.

The transformer/power supply I use is a 9v 1000mA adapter, bought at a music shop, but no brand (made in china).

Could a good quality power supply fix this? A Spot One or something? Is there a better regulator circuit out there i should be using? is 1A my issue?

Cheers
Joel