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.

@clearthinker 1+. Having run large ESLs for decades not only do they hate making low bass (they will do it in a lumpy fashion) but it hampers them everywhere else increasing distortion and killing headroom. You are absolutely right about big power supplies but to that you have to add low impedance output stages or in other terms, a high damping factor to control a large subwoofer driver. A tube amp can have the power supply but unfortunately not the output stage. I had Krell KMA 100s for 20 years and they did make great bass and great everything else for that matter. I would still have them if one hadn't burned out. They gave me a love affair with Class A amps that I can not get away from. I understand why many love tube amps. I am considering buying a pair but, there are SS amps that will provide the same shimmer and effortlessness. The ones that I have heard are all Class A and I do not think this is psychological.  

@sandthemall , a good room and proper placement are essential for good bass but there are other factors that have to be considered to get the job done which is why achieving sota results are so difficult. This is compounded further by the use of subwoofers. Bass has a lot of energy. An explosion is a low frequency pulse. In medicine we use low frequency pulses to break up kidney stones. Put on a 30 Hz test tone and turn the volume up. Listen to your whole house rattle. This energy creates a lot of spurious noise which in simple terms is distortion. It starts with the enclosure the driver is in then multiplies with each surface and loose item. Totally accurate bass is something you can only dream of.

@asvjerry , that is exactly right. The best way to see what your system is doing is to run a sine sweep and measure the results with a calibrated microphone. $300 will get you the mic and the program. If you do not do this you have no idea what you are listening too and all of you will be aghast when you measure your system.

There is no tube amp that can produce accurate bass below 40 Hz. The out stage impedance is just too high to control a woofer never mind a big inductive subwoofer. Class A SS amps with very low output stage impedance is what you want. Parasound JC 1+s are an excellent example. Pass XA200.8s are another. Above subwoofer frequencies or 100 Hz and above tube amps are fine if you like them. The only ones I personally like Atma-Sphere MA2s. They are a great match for my speakers according to many people. I also like supporting hand made in America. Watch this! http://www.atma-sphere.com/en/index.html  

What does a kick drum sound like? What does an electric guitar sound like?

There is accurate bass then there is everything else and all of us including myself are listening to everything else.

Bass is the hardest part of the audio spectrum to get right. Everything wants to resonate at bass frequencies, rooms interfere, distortion in drivers increases dramatically and getting drivers and electronics to put out realistic levels below 40 Hz is difficult and expensive. 

I use an unamplified upright bass to judge accuracy. Still, each one sounds different. Less is more. Bass tends to get a lot of garbage added to it like enclosure resonance. Below 40 Hz it is more about feeling than hearing. You have to learn to listen to what you are feeling. A good example is listen to computer speakers. You hear harmonics of bass tones which will give you the bass line but you feel absolutely nothing. Bass is very powerful. When you get a chance get as close as you can to an upright bass. It is not all that loud but the lowest notes will shake your gut. That is what you want to get out of your system. Good luck, you'll need it.