There are several solutions depending on whether your amplifier is new or old.

Optical cable for amplifier: LogiLink CA Toslink 4.65 Frs from Digitec provided that the amplifier is equipped with Toslink.

Or an HDMI cable type Gembird HDMI (Typ A) - HDMI (Typ A) 4.50 Frs if the amplifier is equipped with HDMI

Otherwise you need an adaptor: LogiLink Coaxial and Toslink adaptor 17.30 Frs from Digitec
+ a coaxial cable: Goobay Stereo connection cable 2x Cinch 4.95 Frs at Digitec the old amplifier is equipped with two cinches
+ a Toslink optical cable as above at 4.65 Frs
Best regards

You can use cinch cable or directly via Hdmi to amplifier

Personally, on my Yamaha amp (which doesn't have an HDMI port), I connected it to fibre optics.

Connected it directly to the TV set, don't know