I have just succesfully installed a QSI sound/decoder in my K-27.
The installation took just 20 mins,
The sound is superb, a vast improvement on the LGB/Massoth combination I had installed until the QSI one arrived here at my supplier (www.dragon-gscale.co.uk).
Surprisingly the cost price is far less by about £40 ($80) than a Massoth or ESU sound decoder, over here.