Question about Yamaha A-S301

An equalizer, I don't know if that's necessary, but maybe it would be better to take a home cinema amplifier, they are also very good for HiFi and have a measuring computer, where you could then adjust the speakers with the built-in equalizer.

You can certainly connect an external equaliser to any amplifier, but then you have to connect the speakers in the same way so that they get the adjusted sound.

With this AV receiver, you will certainly get an excellent sound in stereo mode, and a DAB+ radio is also built in:

Onkyo TX-SR494DAB (7.2 channel, DAB+)