A:AnswerARC is disabled on the TCL tv by default. The following link provides instructions on enabling ARC.
https://support.tclusa.com/televisions-setup-configurations/connecting-a-sound-bar-to-your-tv-using-arc
A:AnswerWithout knowing exactly which system of speakers it’s hard to say exactly. However, the receiver has connections for subwoofers independent from the other channels. Plus the front, middle and rear and center channel so you should be able to connect the existing speakers and still have two that can be used later.
You will need an active sub-woofer and you will connect to the subwoofer pre-out. You will connect a single RCA cable from the receiver to the sub-woofers LFE input.
This is due to a handshake issue which is normal depending on the devices connected to the receiver. If you are powering on the TV first the receiver is looking for an ARC signal. We recommend pressing the source you are about to use on the receiver remote in order to power on the receiver this way the receiver goes directly to your audio and video source and you will not need to cycle the unit for sound.