Thanks Detlof .. what you wrote is the exact result my friend is getting with 4ohms JA30 setup
I think too the 8ohms setting is the best because stays in the middle .. pratically he won't lose the grip on the low frequencies and won't lose the highs presence
I think too the 8ohms setting is the best because stays in the middle .. pratically he won't lose the grip on the low frequencies and won't lose the highs presence