I will second the k88 in the f35. I purchased the f35 about 6 months ago, just to have a different sound. My main amp is a Pass labs intergrated 60, soon to be replaced by pass intergrated 250. I use my f35 with kef LS50 and sub. When I switch set ups, I don’t miss my pass labs. Not saying the Black ice is better, just a different sound I enjoy and don’t get from the pass. For the money black ice is very good. It has very good bass punch for tubes.