I do not have this problem. One needs to use the AUX in if the amp has one. If you don't have AUX any hi ;eve; input will usually work. Phono is low level and will NOT work. I set volume control of amp at my typical listening level, and start the Dot at midpoint which is volume level 5, so tell Dot to set volume level 5 to start with. I usually need to tell Alexa to set volume level 8 so the signal from Dot is high enough to match volume level of my many other inputs to amp as close as possible.
That's all there is to it..