MR16 12V low voltage light bulbs will work on your existing LED power supplies as long as the power supply’s minimum wattage is met. A 50 Watt halogen MR16 light bulb being replaced with 4.5Watt LED MR16 results in a significant power drop which not all power supplies can handle. If after replacing your MR16 and you experience flickering or the bulbs switch off after a period of time this would indicate that your power supply is struggling to cope with the reduced power draw. A temporary fix would be to add a halogen bulb into the circuit to increase the overall wattage.
If you are replacing the power supply the best option is to opt for a 12V DC supply that is slightly more powerful than your total power requirements. Direct Current power supplies produce better results in terms of brightness and ensure the bulb will experience a longer life. Traditional halogen low voltage downlighter would generally have their own power supply, MR16 LEDs use very little power so you can power all the LEDs of one transformer.
You don’t need to run new cables find the first transformer in your run and hook that directly into your cabling and then remove the other obsolete transformers and hey presto you now have low voltage LEDs saving you money and electricity. Please note always consult a qualified electrician.