I have two LED Strips connected together and attached to a basic controller. The issue that I'm having is that the last 20 or so lights of the second strip flicker and don't display the appropriate colors. At first I thought it might be voltage drop so I now have it connected to a 10 amp power supply which should be more than enough to power the number of LED's but still have the same issue.
The strips are WS2812B - 150 pixel each and this is the controller:
https://www.amazon.com/gp/product/B0837FWMVC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I've swapped out the strips and have the same problem.
Any help would be appreciated.
Thanks.
Have you tried powering the strips from both ends? Do you have capacitors installed in parallel with the power supplies to the strips?
If led strips are connected in series may be need a good capacitor in the supply in middle connection.
acjacques:
If led strips are connected in series may be need a good capacitor in the supply in middle connection.
It's also good to run separate power wires, instead of depending on the strip to conduct power to downstream strips.
If your controller isn't working, you could use an Arduino to drive them. 
. At first I thought it might be voltage drop so I now have it connected to a 10 amp power supply which should be more than enough to power the number of LED's but still have the same issue.
Yeah... The resistance of the thin conductors built-into the strip causes a voltage drop over the length of the strip.
There is some Ohms-per-foot or Ohms-per-meter so the farther you go down the strip the greater series resistance between the power supply and the LED, and the greater the voltage drop. That's unrelated to the current capability of the power supply.
I think that reply #1 has the correct idea. You should apply power every 50-or-so leds; you might get away with every 100 but I think that that is pushing it.
FYI, I run 4x60 leds in parallel on a 10A power supply and have not noticed a difference in intensity while powered from one end.
Further, in a worse case scenario, if you have 300 leds at full white (60mA each) and a 10A power supply will not cut it.