Hi @Migo33
Thanks for your post!
As long as your Amp is connected to your TV with HDMI, it doesn’t matter how your DVD connects to your TV - just that the TV gets picture and sound. I assume the connection is either SCART or S-VHS? Either way, the TV will pass the sound on to the Amp - if the TV supports HDMI-ARC and you use that socket for the Amp. You’ll also need to tell your TV to not use it’s own internal speakers (depending on it’s smart-ness) and finally, make sure CEC is turned on in your TV’s settings. If you can’t find the setting, google “CEC” and your TV brand name to find out what they call it.
As @106rallye suggested, keep the RCA connections (unless needed to connect the DVD and TV) between the DVD and the Amp for listening to CD’s when the TV is off. The Amp will prioritise the HDMI input over the RCA input, so the TV will need to be off for CD play.
I hope this helps.
Edit: If you are using a composite RCA connection to get a picture from your DVD to your TV , then you will need to connect the audio RCAs to the TV as well - connecting them to the Amp would result in lip-sync issues. If this is the case, a HDMI-enabled DVD/Blu-ray player might be your best option. There will be a significant improvement in picture quality too.