What is Tight Bass?

@phusis , good for you. It sounds like you are working on a great system. There are no passive crossovers in my system either, wouldn't do it any other way. The best crossover is no crossover, passive at least. In my system there is only one digital crossover for the subwoofers. Otherwise, the Sound Labs operate full range, 100 Hz to 20 kHz.  

@clearthinker, there are times when I wished I had not sold those Krell amps. It was not until I got the JC1's that I got that magic back. The Atma-Sphere amps are also class A. There are so many reports of their effectiveness with my speakers, hard to ignore. I'm warming up to getting a pair of MA2s. The alternatives are the JC1+ and the Pass Labs Xs 300s. That is quite a stretch money wise. I'll use my current JC1s to drive the subwoofers.  Do the Pass amps add another $60K worth of sound quality over the other two amps? The problem is there is no way to know without trying them which is difficult to do. I am probably not going to make a $60K gamble. The Atma-Spheres are enough of a stretch.

Speaking of Atma-Sphere, it seems we have not heard from Ralph lately. I hope he is OK.

Tight bass is very simply: when the signal stops, so does the woofer (in fact, the entire loudspeaker). To not "stop on a dime" is to produce "overhang". In the world of loudspeaker design, there is the concept of "critically" damped woofers, as well as over-damped. A Google search will lead one to lots of literature on the subject.

IMHO "tight" bass refers to the system's ability to cleanly differentiate [in a mono mix] between a double bass plucking and an underdamped bass kick drum beating at the same time without mixing the two up to any degree. many systems can't do this as well as they ought. 

Tight bass relates to timing.

When a Bass note is exercised if it reverberates or cant musically keep up with the song its timing is off and it's called not tight...

You could add "tunefull" and you bring in timbre and definition as well.

NAIM = Tight Bass!