You need a proper amplifier that can ideally supply the speakers with 85W. Ideally, the amplifier should have optical inputs and your PC should have an optical output so that the connection between the PC and amplifier is virtually loss-free. If no optical connection is possible, simply connect via normal audio.

For use with your PC, I would rather recommend active studio monitors (have a look at https://www.digitec.ch/fr...). Your DAC then serves as an audio interface and preamplifier, the speakers can then amplify the signal even more (because they are active).

The Klipsch R-51M are passive speakers that are more suitable for hi-fi or home cinema. To operate them, you need a proper amplifier or receiver.