Thanks Ingolf,
actually I would prefer to test several solutions before I buy one. Forgot to mention the Yamaha DXR 12 (?) which should also be a considerable option.
Unfortunately it is impossible to either test the Matrix Q12A / Matrix gt 1000 / Atomic CLR - at least here in Bremen (Germany) and the surrounding area, so I will most likely have to rely on other peoples opinions / reviews / videos you can find on the net. ( There are a few good reviews . e.g. look in youtube - Pete Thorn is reviewing both the Matrix GT 1000 as well as the Atomic CLR - he is a great guitar player and makes really nice demos)