Speaker recommendation

I've been away from this forum for some time so forgive me if this thread is redundant. Simply, I need more bass response from my kit. I am running a Belles Hot Rod 150A and Rogue 99 Mag thru PSB Silvers. I like the overall sound but have been wanting more base. I tried shi-shi cables...nothing appreciable to warrant the cost. I swapped out different combinations of 6sn7s, including gt's and bad boys, vt 231s including TS round plates and metal base, and 5692 red base. The sonic differences were notable but the bottom I was looking for was elusive.
Frustrated, I bought a Definitive sub that more than delivers. At about 18" cubed, it takes up room that I now need. I want to get rid of the sub and upgrade to a speaker that delivers it all without amphitheater size and the need of a second mortgage. I'll listen to all suggestions. Thanks in advance for you advice, humor and criticism.