[MTCB Software Development] KaMu1219:
I use Tasker for this. Works quite good, but not 100% reliable. Didn't find any better solution yet.

Put this code in a file and import it in Tasker

<TaskerData sr="" dvi="1" tv="4.9u4m">
<Profile sr="prof5" ve="2">
<cdate>1486586483928</cdate>
<edate>1486586483928</edate>
<flags>2</flags>
<id>5</id>
<mid0>3</mid0>
<App sr="con0" ve="2">
<cls0>com.maxmpz.audioplayer.StartupActivity</cls0>
<flags>2</flags>
<label0>Poweramp</label0>
<pkg0>com.maxmpz.audioplayer</pkg0>
</App>
</Profile>
<Profile sr="prof6" ve="2">
<cdate>1486586590616</cdate>
<edate>1486586827326</edate>
<flags>2</flags>
<id>6</id>
<mid0>4</mid0>
<App sr="con0" ve="2">
<cls0>com.microntek.radio.RadioActivity</cls0>
<flags>2</flags>
<label0>Radio</label0>
<pkg0>com.microntek.radio</pkg0>
</App>
</Profile>
<Project sr="proj0" ve="2">
<cdate>1486586412915</cdate>
<mdate>1499671684582</mdate>
<name>Base</name>
<pids>5,6</pids>
<tids>3,4</tids>
<Img sr="icon" ve="2">
<nme>hl_aaa_ext_home</nme>
</Img>
</Project>
<Task sr="task3">
<cdate>1486584230943</cdate>
<edate>1499671600344</edate>
<id>3</id>
<nme>Radio mute</nme>
<pri>100</pri>
<Action sr="act0" ve="7">
<code>664</code>
<Str sr="arg0" ve="3">am</Str>
<Str sr="arg1" ve="3">AudioManager</Str>
<Str sr="arg2" ve="3">new
{AudioManager} (Context)</Str>
<Str sr="arg3" ve="3">CONTEXT</Str>
<Str sr="arg4" ve="3"/>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
<Action sr="act1" ve="7">
<code>664</code>
<Str sr="arg0" ve="3"/>
<Str sr="arg1" ve="3">am</Str>
<Str sr="arg2" ve="3">setParameter
{} (String, String)</Str>
<Str sr="arg3" ve="3">ctl_radio_mute</Str>
<Str sr="arg4" ve="3">true</Str>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
<Action sr="act2" ve="7">
<code>664</code>
<Str sr="arg0" ve="3"/>
<Str sr="arg1" ve="3">am</Str>
<Str sr="arg2" ve="3">setParameter
{} (String, String)</Str>
<Str sr="arg3" ve="3">av_channel_exit</Str>
<Str sr="arg4" ve="3">fm</Str>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
<Action sr="act3" ve="7">
<code>664</code>
<Str sr="arg0" ve="3"/>
<Str sr="arg1" ve="3">am</Str>
<Str sr="arg2" ve="3">setParameter
{} (String, String)</Str>
<Str sr="arg3" ve="3">av_channel_enter</Str>
<Str sr="arg4" ve="3">sys</Str>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
</Task>
<Task sr="task4">
<cdate>1486584230943</cdate>
<edate>1499671710329</edate>
<id>4</id>
<nme>Radio unmute + Poweramp Pause</nme>
<pri>100</pri>
<Action sr="act0" ve="7">
<code>664</code>
<Str sr="arg0" ve="3">am</Str>
<Str sr="arg1" ve="3">AudioManager</Str>
<Str sr="arg2" ve="3">new
{AudioManager} (Context)</Str>
<Str sr="arg3" ve="3">CONTEXT</Str>
<Str sr="arg4" ve="3"/>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
<Action sr="act1" ve="7">
<code>664</code>
<Str sr="arg0" ve="3"/>
<Str sr="arg1" ve="3">am</Str>
<Str sr="arg2" ve="3">setParameter
{} (String, String)</Str>
<Str sr="arg3" ve="3">av_channel_exit</Str>
<Str sr="arg4" ve="3">sys</Str>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
<Action sr="act2" ve="7">
<code>664</code>
<Str sr="arg0" ve="3"/>
<Str sr="arg1" ve="3">am</Str>
<Str sr="arg2" ve="3">setParameter
{} (String, String)</Str>
<Str sr="arg3" ve="3">av_channel_enter</Str>
<Str sr="arg4" ve="3">fm</Str>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
<Action sr="act3" ve="7">
<code>664</code>
<Str sr="arg0" ve="3"/>
<Str sr="arg1" ve="3">am</Str>
<Str sr="arg2" ve="3">setParameter
{} (String, String)</Str>
<Str sr="arg3" ve="3">ctl_radio_mute</Str>
<Str sr="arg4" ve="3">false</Str>
<Str sr="arg5" ve="3"/>
<Str sr="arg6" ve="3"/>
<Str sr="arg7" ve="3"/>
<Str sr="arg8" ve="3"/>
<Str sr="arg9" ve="3"/>
</Action>
<Action sr="act4" ve="7">
<code>443</code>
<Int sr="arg0" val="1"/>
<Int sr="arg1" val="1"/>
<App sr="arg2">
<appClass>com.maxmpz.audioplayer.StartupActivity</appClass>
<appPkg>com.maxmpz.audioplayer</appPkg>
<label>Poweramp</label>
</App>
</Action>
</Task>
</TaskerData>