Best Class A amp with SLAM

Sounds like you would be happier with new speakers, not new amps. Smaller woofers = quicker bass = slam……

Have been to a lot of live venues and never heard much slam.

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...ditto what Map said.
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Maybe I should have kept them and had them recapped. They were almost 25 years old and it was time for a change. As far as speakers go, I have Wilson Maxx II's and am amazed each and everytime I listen to them. As far as amps go, the Pass Labs are smoother and I'm not in to only slam, but I do miss that attribute of the Krells. My X100.5's will suffice for now. They're great amps. As I said, perhaps I'm remembering the Krell's through rose textured ears.

You should add to your audition list the Electrocompaniet AW series monoblocks: AW180, AW400 and AW600 (Nemo)

Smooth sound and can handle loads down to .5 ohms.

I also own the Pass XA.5 series, and although I love mine, it seems that these amps are a bit reticent in the bass/slam department. I've read that enough times from enough different people that I'm pretty comfortable attributing the issue to the amps.