Missing tube integrated for Klipsch Forte III?

2 weeks ago i acquired and set up the forte iii's in my 25x35 basement (8ft ceilings).  i paired it with a gorgeous yamaha as-2100 - man that amp is beautiful and solidly built.    granted, both the forte's and that amp aren't really broken in yet BUT (i hate) i am missing that low end bass presence that i hear so much about from tube people.   they all talk about "bass slam."   it's not that the yamaha doesnt deliver, but i'm just not feeling it as a slam.   i understand the primaluna evo 300 uses EL34 tubes and are supposed to be highly musical, dynamic, and able to slam.   reading all those reviews leaves me tempted to try to tube route.   thoughts?   looking for real low end at low volumes with great detailed resolution up top (but not too bright).   i do love the build quality and aesthetics of the yamaha - would be hard to see that go on a trade.