only call sox when needed

atom

@@ -1244,7 +1244,17 @@ do
 			case "$extendedtype" in
 				*'Musepack '*)
 					decodeMpcdec
-					sox_needed=1
+					if (( ${destinationnormalize["$destination"]}))\
+					|| (
+					[ -n "${destinationfrequency["$destination"]}" ]\
+					&& (( ${rate:-0} != ${destinationfrequency["$destination"]}))\
+					) || (
+					[ -n "${destinationchannels["$destination"]}" ]\
+					&& (( ${channels:-0} != ${destinationchannels["$destination"]} ))
+					)
+					then
+						sox_needed=1
+					fi
 				;;
 				*)
 					decodeSox