There are not that much of online radios available for their listeners that are playing live musical shows for their listeners. There are some that occasionally plays live musical programs but very few of them actually is full time live music based radio like MDR Sputnik Soundcheck Channel.
MDR Sputnik Soundcheck Channel official website address is /www.sputnik.de
Popular Germany Radio:
Radio Evangelist Bright
100 Top Schlager
If the Radio is extremely choppy and stops every 5 seconds, try listen to this Radio at different time.
Not all Radio Stations function for 24 hours everyday. If you can't listen to any Radio, try to listen at different time, as the Radio Station may stop during midnight according to its own country time zone.