I have used them with horns mostly and 15" bass cabinets. At the moment I am using a type 50 amplifier which is good for a couple of watts or the 503pa's which I love. I recently built some very efficient and large 50hz bass horns which I am really enjoying and need far less to drive. I use Elrog 845's, Mesh plate 300b's and Western electric 310A's in the 503pa. The LM are basically mono versions of the 219ia without a preamplifier. Prior I was using a LM 518ia, loved the amplifier but really hated the cross talk and therefore went down the mono block road.