The answer isn’t so simple. The DM3730 used on the Beagleboard-xM is more powerful because of the additional DSP, but there is currently no support in the current Linux kernel for the DSP processor. The DSP was supported in Linux kernel up to V3.4, using SysLink to communicate between the ARM processor and the DSP. SysLink has been replaced by RPMSG/RemoteProc, but there is currently no support for the DM3730. The new Beagleboard-x15 will be supported.
However, the BBB with the TLV320AIC3104 audio cape does work, but if you require a microphone, you will need additional circuity because the audio cape does not support bias voltage required by the microphone.
Regards,