Just a minor update. Andrew and I are working on a TZX version of Casduino. Much more complex than loading .cas files but if it works it will open up more possibilities.
We have also added Dragon/Tandy .cas files to the Casduino but without one of the computers ourselves it's very much at an alpha stage and may well require the volume control mod to the amp.
Also there is now a Facebook page where you can read latest development, ask questions, and even order a prebuilt PP9 version. The Facebook page can be found here.