my kenwood ddx9903s should have an output of 5v. At first I didnt realize there was an input setting so it was set at 1v for all inputs, with gains on sub amp at roughly 4v input there was not much bass. I found the input voltage on the twk88 in a quest to figure out what setting I missed to not have any bass. brought that up to 5.6v for all settings, but have since dropped it back to 2.8v. had to max the sub amp to get much action at all. with gains set sanely, there not much there. and way less than there was with the ms8 as a direct swap