Hello, I am pretty new to the SP, and I am aware that it warns users to only use the PSB-1u as a power source, but I just got a PSA-120s. It is 9 volts, boss/roland brand and seems to work, though I am hesitant using it as it is not the PSB-1u. Is the warning simply to sell that type of supply, or will using the PSA hurt the unit?

The technical specifications of the PSB-1U are as following:

INPUT: 100-240V~ (A001760)
50/60 Hz 0.5-0.25A
OUTPUT: 9V === 2.0A

... if it matches those of your PSA then it won't matter. If it's different however it could definitely damage your hardware, even if it seems to be working fine. Using the wrong kind of power supply definitely causes internal chips to fry in worst case scenarios, it's really best to have either the original supply or one that matches exactly.

I've just checked by the way and see there's more information on the power supply of my SP-555 than my SP-606 one, both being a PSB-1U. I can't quite discover if they are different, but perhaps it's really best to get the original supply instead.

One thing is certain though, a 12V supply for example would kill your hardware in a matter of weeks or perhaps days. That may seem obvious, but a supply with a different kind of ampere will have the very same effect.

yeah i lost mine...but then i just ordered a new one from roland...dont use any other its not worth it....