Either or none will work. The key is not to exceed the Vf and/or rated current as I mentioned in my earlier post. The specs for the 10 watt Royal Blues I have is 9 to 10 volts Vf and maximum current of 900 milliamps. The standard blues & whites have max current of 1000 milliamps. Warm whites are down at 900 milliamps like the Royal Blues. The output voltage of your power supply will determine what current the LEDs run at if you don't use any dimmers, resistors or other current limiting device to protect them. Therefore you want a very stable power supply that has a Vf of about 9 volts. Lower voltage is probably better. Due to manufacturing variances, it's likely that each one of your LEDs will run at a slightly different current when provided with the same voltage if you don't use a current limiting device. That's why most folks opt for constant current drivers instead of a constant voltage power supply.
I use fairly inexpensive dimmers to keep my Vf less than 9 volts for all colours of LEDs I'm using in my fixture. This provides a bit of a safety margin from premature burnout. Early in the build I did some current testing & found that there was as much as 80 milliamp difference in current for some of the LEDs when provided with the same voltage. Photo of the dimmers & power supplies follows. I actually cooked the RB dimmer recently but looking back I wonder why it took so long. I've been running too many LEDs on the two dimmers running my outer rails of LEDs for a couple of years now. There are 9 LEDs per rail, so the 8 amp dimmers have been running at close to maximum rating. The two dimmers for the center rail run 4 and 5 LEDs respectively, so they're well within their rating. I have 5 more dimmers on order & will be splitting the load so each outer rail is run the same way as the center one. So the photo will have two more dimmers added below the two on the left. Not sure why the RB dimmer cooked before the 10000K one since it runs 8 LEDs while the 10000K runs 10. Only thing I did was install a couple of larger power supplies recently. Also been running the voltage at 8 to 8.5 for a while now, not as low as the settings in the photo.
