Turntable-Amplifier-Speaker configuration question.

Sorry if this is a silly question, but I am getting back into home audio for the first time in many, many years. I recently got back into vinyl and purchased a Technics SL-1500C with a pair of KEF LSXII speakers. It sounds great, but apparently the amount of volume I can get to the speakers is limited because of the Phono to AUX routing I need to use into the speakers. I tried using a Denon amplifier to see if I could get a louder signal, but that didn't help. I am wondering if someone could suggest a setup for my turntable that would get me the fullest possible range of volume. I am open to starting with replacing the speakers and purchasing a new amplifier/reciever.