Setting up Pianoteq with a DP - hissing noise problem solved!

I thought I would share my experience of setting up Pianoteq to run through a digital piano in case this helps anyone else.

I wanted a complete solution that gave me an attractive, convenient installation using Pianoteq.  I did not want any visible wires, speakers, amplifiers etc.  I decided on a Roland HP 605 as this has USB MIDI out and also has an AUX IN.  I built a mini PC to run Pianoteq that is located behind the back board of the Roland so it is not visible.  I made a small box with a push button switch and an LED which connects to and switches on/off the PC.  This small box is located on the top of the piano and is the only visible component.  I connected the USB MIDI from the Roland to the PC, the sound output from the PC to the AUX in on the Roland. Once I had installed and configured Pianoteq and the other software so it automatically starts when switched on, I removed the PC Screen and keyboard.   Now I have what looks like an ordinary digital piano.

To play the piano, I push a button to turn on the PC and push a button to turn on the Roland.  Then I use the Menu on the Roland to turn Local Control OFF and I am ready to play.

I found a slight harmonic resonance in the cabinet but using the graphical equaliser in Pianoteq I was able to smooth this out BUT I found that there was an annoying background noise/hissing from the Roland speakers.  At first I thought this was the sound card on the PC so I purchased a Behringer UCA222 and connected this.  The problem did not go away.  Finally I realised that the noise was due to the USB cable that was sending MIDI from the Roland to the PC.  Unlike a standard MIDI cable which is electrically isolated, a standard USB cable connects to the electrical systems of both the computer and the piano.  Electrical noise from the computer via the USB cable was causing noise in the speakers.  I researched this and found I could buy a USB ISOLATOR on eBay for about $20.  This plugged into the USB port on the computer and then the cable plugged into this.  PROBLEM SOLVED.

I am very happy with this setup.  It looks smart, sounds beautiful and is easy to use.  Many thanks to the team at Pianoteq for such a superb program.