So in advance, I already make some speculations with the Zimme and the farmer. But my test possibilities are limited. so then I had the problem that the DD had simply not brought the level any more which he should have done at this volume. It was just quieter than before to the same raised level. So then I proceeded as follows. First Chinch hung to another exit of the HU. = still quiet Then another chinch cable geno mm tested on sub-out, and rear out from HU = the same DD removed from the housing, both coils tested = both Ok. So at some point it went again. But now I got it again. Again quiet level. So I now took a multimeter. 50 HZ tone, and turned on. With the connection clamp of + and – 31 volts out. With the LS terminals strangely only 25 volts. AMP: is the AT1500 (considerable high efficiency) sub is at 0.5 ohms. That would give at 31 volts almost pi times thumbs 1.9 KW and at 25 volts but only 1.2 KW. How can that be? Now the funny thing about the thing. WHEN I could turn louder at the HU “could” (was already max turned up) then I would have the same level as before. So as it should have been normal. Now we 3 don’t really know what it could be anymore. Hu event? Preamp 4 volts defective and only runs on 2 or so? The wiring is OK. Speculate with us, and try to help me.