If I double click on an iso file in ambient I can browse through it w/o extracting it before.
But the buffers of this device are always set to 1 (use "AddBuffers @x:" to see how much buffers are set).

I can change the buffers afterwards with AddBuffers command, but how can I set the initial default buffers?

Btw, reducing the buffers with a negative number (f.e. AddBuffers @x: -100) doesn't seem to work!?

It's likely that the virtual filesystem handler doesn't use dosbuffers but its own internal buffering system.