Disklavier

I am also looking for a speaker system to use with the DKC-850.  The Amp hiss from the build in piano  amp is too noticeable.

What I am looking at is a SOUND BAR  made for flat screen TV.  They are long and thin and can be mounted under the piano, and most include a wireless  SUBWOOFER...  

There are also YAMAHA  bars , that are all in one..  bit larger  and more money. 
Example of the  Yamaha is  YSP-4100 Digital Sound Projector with the dimensions of  40-7/16"W x 8-5/16"H x 3-9/16"D BUT costing $1700.   Lower cost ones are from Samsung, Sony, Polk  etc  

These sound bars include an amp, thus you only need to run the power and RCA sound cables to them.  Mounting will be key, with lots of felt to minimize vibrations. Wireless subwoofer can be place anywhere..

Like to hear others thoughts on these.