Ok Vincent, sorry - it sounds like things are basically set up ok. I will try to help.
I suggest that you list out and send to the forum the all of the steps you go through to set up for a session. For example, something like this:
- Start Vienna Ensemble Service
- Start Pro Tools
- Create a Session
- Create an Instrument Track
- Add an Insert Plugin to the Instrument Track of "Vienna Ensemble"
- Select "Connect" in the plugin (does it connect properly and an Ensemble instance pop up?)
- Set the Instrument Channel output to "Analog 1-2"
- Set the Instrument Channel input to "no input"
- Create a MIDI channel
- Set the MIDI channel output to "Vienna Ensemble 1: Channel1"
- In the Ensemble instance: insert an instrument, and set it to channel 1
Also go to Pro Tools menu Setup -> MIDI -> Input Devices and list the contents. Are any of them checked? (If anything is checked, uncheck it - even if you think you need it. It will be a valid test.)
Are there any other MIDI dievices or sound card hardware (other than the Pro Tools hardware) on the machine?
When you say feedback, I assume that you mean once you play a note, it keeps on playing many times? (That is, it sounds like a MIDI problem, not an audio problem - right?)
That's all I can think of to ask. If you list all of this, I will try to see if there is a problem.
--Dirk