My Sonus Faber Amatis have weak bass even though I'm running ML 536s--800 w/ch into 4 ohms

I don't know about packing, but assuming your speakers have rear wall reinforcement and you haven't put them in a bad modal location your next option is some room treatment.

In a very reflective room the speakers will sound excessively bright, also known as "lacking bass."  By taming the high frequency energy in the room the bass is allowed to emerge like an old shipwreck appearing at low tide.

Thanks all. I'll give it another try. I had 803d2s before. I thought they were to bass light. I moved up to the SFs hoping that would solve the problem. It didn't. I moved up to the MLs from a Classe CA-2200. The MLs have twice the power of the CA-2200. That didn't really make a difference on the low end. I've tried every cable possible. I've moved them around to every conceivable location in my room (which is somewhat limited by the fact that it's our living room, and I can only get away with so much with my wife. Thanks again.

BTW, not looking for crazy bass, but there is a completeness of sound that I get with the subs that I don't get without. The mids and upper frequencies also sound better with more fulsome bass. Not sure why, but that's what it is. I will say that the mids and hi frequencies are somewhat forward (not sibilant or harsh, just top heavy. But that could be because the bass is so weak). I listen to jazz and classical mostly. Bass drums, kick drums, double-basses, etc., are there but not there.

BTW, if your room is reasonably rectangular, I suggest examining the results from the AM Acoustic room mode simulator here.