"Slam"--what is it, is it really accurate?

If the speaker cannot "slam", no amp will help. The speaker is more important in the slam equation than the amp. There are lots of amps that will make a capable speaker produce slam, but few speakers that have the dynamics to do it.

Anyone who thinks that it is an audio thing does not get out to hear live music much. Even a small drum kit can smack you hard. Course, most audiophiles don't go out to live music, they just talk like they do.

Slam is when you have a speaker on stands and your grandchild runs a football route into one of your speakers and it gets knock up against a wall like body check in hockey. It is very accurate and I hope it never happens again.

Slam can startle and slam can be subtle. It doesn't take much for certain notes to energize a room so it's not all in the purview of bass notes and loudness (volume). It's only because bass and loudness have been the topic of many a discussion when it comes to slam that that is what most folk think of when it's mentioned.

Having said that, I believe it's the speaker that delivers the goods.

All the best,
Nonoise

Alright, so maybe we're talking about different things when it comes to slam. For me, it's about when a solid bass note comes out of nowhere and you can both hear and feel it in a gutteral way. In my experience, it takes removing room resonance, electronic overhang, and noise out of the equation for those bass frequencies to be fully resolved and to have the fullest aesthetic impact. However, I also acknowledge that you can get there by leveraging uneven bass response in speakers, untreated room loading, and other "inaccurate" characteristics to make bass kick pretty hard. But in this case, you'll be trading in many other important aspects of the sound in order to maximize that bass impact.

Like others have mentioned, speaker design will play a big part. Ported speakers in general will "bump" more than other designs due to the resonant frequency of the port emphasizing at that frequency. It's not a completely even response, but it does give you that sense of drive and bass dynamics. That can be pretty fun if done well.

It's the room before the rest. Then it is the proper pairing of speakers and amp.

Case in point, when I first moved into my room, my system sounded fine but the bass response was not very good. I added treatments installed a proper rack dialed in the speaker position and then voila, Slam!

My system is nothing outrageous but I think that I am fortunate to have found a good synergy between all my components.

My slam test reference recording is the overture to Verdi's Rigoletto, the London Symphony Orchestra with Bonynge conducting, London FFRR OSA13105.