I bought the Spdsx from Roland while i was in Dubai, so it's running on 220 watt. Now i'm back in canada where we use 110 watt. Is there anything else then buying a power converter that i can do?
No, not unless you have a cable several thousand miles long !!
It's running on, probably, 9 volts DC, so all you need is a DC converter with the appropriate plug to fit physically and electrically in whatever country you need it for.
The original one would be for 220 VOLTS, rather than watts ! You need to check also that the frequency is right - they're usually either 50 Hz or 60 Hz.
One other thing, if you don't use a Roland adapter, is that the power rating (in milliamps) is the same as the original, and another is that the POLARITY is correct for your drumbox. Check the little picture of a 'C' with a dot in its middle, showing + and -.
Best bet, order a proper Roland 'wall wart'.
Here in UK with 240 volt supply we use 240 to 110 volt transformers to run 110 volt equipment. As the power required by your Spd-sx is minimal the cost for one will be reasonable Example
The power adapter is a Roland PS8-1U. My guess is that it works everywhere on earth, provided you have the right AC plug to fit your wall socket. You can test this by asking Roland Canada for the part number of the AC adapter for the SPD-SX. If it's a PS8-1U, you already have one.
If you read the specifications on the power adapter, you should see that it accepts an input voltage between 100V and 240V, with frequency between 50Hz and 60Hz. Because it's a switching power supply, it automatically takes whatever voltage is coming in and converts it to 9VDC out to the SPD-SX.
So my answer is - use what you have, with possibly a replacement AC cord for Canadian wall sockets.