The Black Diamonds are the loudest per watt, so the least likely to be overwhelmed. For the Skars, you'd probably want a passive crossover network, a pair of these would do: https://www.amazon.com/Audiopipe-Crossover-CRX-203-Passive-Tweeter/dp/B00K505K32/ref=asc_df_B00K505K32/ That would let you use a 2-channel amp, like you would with other separates. The midwoofer will use more of the power because bass takes more power.