The designer of the Inner-tube/Innersound tube amp has been using the Eros to voice this product.He has been using a passive crossover on the top-end {6db/oct.}and lowering the crossover point.Very large improvement.I am completely supportive of passive {Dahlquist DQ-LP1 style}crossovers for the upper frequencies.The active units introduce grain and glare,unless extremely expensive.The latest panels {MKII]are more dependable than the original.Good Luck!