I have two suggestions for Music Shield V2.0.
Recently I combine Music Shield V2.0 (SLD01104P) and W5200 Ethernet Shield (SLD91000P) together and hope to create an internet radio player. But unfortunately the Ethernet does not function at all. I checked the schematic and found two conflicts:
Music Shield V2.0 leave MISO buffer always enabled, .i.e, it interferes MISO wire no matter its SS pins are pull-low or not. This makes Music Shield V2.0 incompatible with all other SPI shields. It could be better to make MISO buffers enabled according to its SS pins, similar to what have been done in W5200 Ethernet Shield.
D10 is a popular SS pin used by many SPI shields. It will be great to add jumpers for SD card SS pin connecting among D10, D9, D8, D7, and VCC to disable SD card when not enough pins available, and perhaps D11, D12, D13 for Leonardo/Mega.
I personally appreciate Music Shield V2.0. It has the potential to accept external feeding data, which make it an attractive prototyping board. Hope you can consider above suggestions in next revision to make Music Shield even better.