(Feel free to edit the title if you find a better way of describing the "transport" aspect of this problem.)
The problem is this: I'm trying to set up my Zoom H2 in Reaper via the Asio4All driver, so that I can connect multiple interfaces for input and monitor the mixed output (while recording) via the onboard soundcard. However, as soon as I enable the H2's input in the A4A-control panel, the project no longer "transports" when I hit Play or Record, i.e. the position indicator remains stationary, the timecode does not progress and no playback is heard. I don't even have to actually hook up the H2 input to any track. It's simply enabling it that triggers this.
With the H2's own ASIO driver everything is working as expected but that way I'm restricted to using the H2's in- and outputs only.
I'm using Asio4All v2.10 and Reaper 3.75/4.0a41 on Windows 7 SP1 32bit. In the process of investigating this I've already updated all audio drivers as well as the H2's firmware to the latest available versions.