[noggin]

24p / 10-bit / HDMI 2.0 from here onwards...a peek into the future...without a Delorean !

You will need a compatible 4K HDMI 2.0 10-bit TV to take full advantage of these devices.
10-bit Video gives over 1 Billion colors vs 16,777,216 for 8-bit, see HERE for further details.
Even though these devices can decode 10-bit, video output will be 8-bit only due to lack of video player Software support (this includes Kodi)

• The new AMLogic S905 has a fresh out of the wrapper, Android Lollipop 5.1.1 SDK, new Linux Kernel and comes with upgraded 10-bit / HDMI 2.0 tech specs compared to the S812-H's.
  
• Excellent AMLogic VPU Hardware deinterlacing when using the amcodec decoder. However Android mediacodec uses inferior ff-mpeg2/h264 Software deinterlacing.
  
• Speed is a tiny bit quicker compared to a Lollipop equipped S812-H device, but with a reduced number of cores in the GPU/VPU.
  
• HD Audio Passthrough is activated in Android API Level 22 Firmware and will work when Kodi finally supports it in Krypton.
  
• As all this is very new, users need to be aware the Firmware is immature with bugs currently being ironed out.
  
• 3D MVC (half res.) is a mixed bag too.
  
• Hi10P H264 Anime decoding is not supported on the AMLogic S905's.
  
• Even bug free 10-bit video output is an unknown quantity at this stage, and there are Hardware Problems with current SoC's.
  
• After sales support is usually a BIG problem with dirt cheap AML Android devices.
  

S905's can be used as Fast cheap, 10-bit decoder, HDMI 2.0 boxes for those on a budget. If you can find one with decent firmware they represent good value, just beware of the current bugs for full Kodi feature compatibility.

Anyone have any recommendations of a box with decent firmware? When I google S905 I get a bunch of results, most of which are around the $50 mark... which sounds too good to be true.

ODroid C2 is looking promising (LibreElec builds are appearing - though early days and so they have some very rough edges)

Wetek have some S905 boxes coming soon. Believe me, Wetek's support for their boxes is in a different league to most of the other box makers. Regular updates, Android and OpenElec (could be LibreElec soon I guess) support, and a team who listen, answer posts here and on their own forums, and who deliver a quality product. They've implemented HD Audio bitstreaming and PCM multichannel in Android on the S812-based Core as a recent update for example.