If it is a problem with multichannel AAC, all the latest Roku's can decode multichannel AAC. It might solve your problem.
Roku devices do not support AAC pass-through. Instead, Stereo AAC is transcoded to PCM stereo.
Roku TVs and some Roku players decode 5.1 AAC to PCM stereo for headphone, internal speaker, and HDMI/ S/PDIF (optical) output. However, Roku devices that support Dolby Audio decode connected via HDMI or S/PDIF (optical) to an A/V receiver that also supports Dolby Audio, will convert the audio to Dolby Digital 5.1.