"Musical" subwoofers? Advice please on comparing JL subs

   

  If you look at the way a Class D operates is chops the signal up similar to digitizing it. Yes they can make them sound pretty good with lots of power, but it don't sound as good to me.

Was your assessment of both subwoofers compared in the relitivly same position during the same A/B listening session?

Just as an opposing point of view, I'd like to say that I have done a fair amount of comparison evaluation of Class A/Ab and Class D amps.
The switching power supplies are another story all together as I feel they don't cut it with powerful subwoofers.  The heavy toroidal type transformers with a lot of reserve capacitance just has the massive headroom for large dynamic power demands.   Take a look at the Bryston 28B3 monoblock amps (Google image these monsters and you cannot believe the power supply section), They are pumping out around 1800 watts into 4 ohms with what I am told is almost unimaginable dynamic power when under heavy loading.  I have not had the luxury to try these out yet, but I'd love to.
I have a nice Parasound A51 amp which is Class A operation up to around 10 watts output and then migrates into a Class Ab amp when the power goes up as it can do 400 watts per channel into 4 ohms.  It's a great amp, very smooth and musical.  I was sent one of their new design Class D amps to try out and I must say that on the lower end, it was impressive with its 600 watts per channel and gut wrenching bass response.  I did not like it much on the upper mids into upper range as I found it harsh on my ears after a period of time listening.  But it is not an expensive amp and it uses the typical off the shelf Class D power modules which many companies elect to go with.
From there I installed a pair of Anthem Statement M1 monoblock amps which are gorgeous Class D slim pancakes vs. the A51 Parasound A/Ab amp.  The M1's are connected to my main panel via dedicated 240V 15 amp circuits, one for each amp.... and running them on 240V vs. 120 V 20 amp lines made a huge difference in performance.  At  4 ohms, these babies pump at a minimum of 2000 watts per channel and all I can say is that it was a major WOW moment when I turned them on with some music I am very familiar with.  Massive low end, super silky mids and smooth/articulate Upper range.   It was almost too good to be true and I wanted to hear how they were on me after a night of long listening.... just fabulous, absolutely no harshness at all.  These amps have liquid cooled output devices and very proprietary feedback loop design along with an excellent power supply section.  There are no off the shelf Class D modules in the M1's they are all Anthem of Canada design and built in Toronto and expensive at $7K.

Now after a few days of use, I decided to swap out to my trusty Parasound Halo A51 A/Ab amp just to get back into Class A again.  After about 1 hour of use, I removed it from the rack and went back to the heavenly M1 monos.... no contest!   The Class A amp was just blah and lacking in articulation vs. the M1's in Class D.  The M1's are still here, I didn't use the A51 for about a year or so until I decided to use it for a surround system where it is doing duty as the center/surround/rear speakers which it does well for.  But for critical listening on two channel stereo vinyl with my VPI Ares3/SME Series IV tonearm/Ortofon A90 MC, not much will come close to the M1's.   Again I have not had the luxury to try the monster Bryston's, but at $30K for a pair of those monoblocks, I might be waiting.

Getting back to Northman and his original quest for information;  I still think that you should get yourself the Axiom EP500V4 subs at $1500 each in real wood veneer and with the new variable phasing.  A pair of these I believe will outperform most anything you will find under $2500 each.  Plus if you are not happy, they give you a 30 day trial, no questions asked for return; so you cannot hurt yourself.  I think they even pay the return freight.... that's because hardly anyone ever returns their stuff. :)
If I were in your shoes, I'd get a pair of the ones you are interested in and the EP500's and do an in home comparison to make up your mind on suits you best.

@slimpickins5  I don't doubt that there are some very expensive Class D amps that will sound great. They are way out of my budget, mostly for the 5% who make too much money. There are some modestly priced units that sell within my budget, but until recently they weren't very good.

The PS audio product reviewed in Stereophile December 2020 issue are probably good sounding. Especially in the bottom.

They are still PCM or PWM. Pulse Code Modulation or Pulse Width Modulation are sampling techniques that quantify analogue into pulses or bits. Bits are bits. Bits are digital.You can turn a square wave (bits) into a sine wave with filters, the same basic technique used in Class D or PWM amps. I prefer the purity of an analogue signal from start to finish, vinyl to speaker cone.
Also, they use chips to do the work. That's solid state. I choose analogue and tubes.

Well I don't think that you can compare modulation states as bits 1 and 0.  
They are not computer code.  So I don't see the comparison.  Its just a difference in when the solid state device is firing or operational as in using current and making heat.  It is how the analog signal is amplified.  Analog in, analog out.  My vinyl goes in in pure analog state and comes out the same way.   Trust me, it just sounds much more articulate, defined and full with high dynamic range vs. my Class A amp.  Its much better in my opinion.   And I am not degrading the devices with excessive heat or worse yet degrading tubes which really don't do well with heat and other degradation with age, loss of vacuum, etc.   I think that Widows 10 is far better than Windows 95.