Class A vs AB

Here is the balance the way I see it.  "Current" is what pushes the woofers, and this is what makes bass.  For super efficient speakers, the highs and mids are loud without much current which can hinder the movement of the woofer cones, thus giving you less bass.

@hjdca  It does not work this way. You do need more power (not current, since Voltage must be present for current to be present and the two together are power) to do bass frequencies since there is so much more energy there. But what you're saying about high efficiency speakers is simply false. 

   I am considering a pair or Arandal 1528's (84 db sensitivity I believe, 4 OHM) I understand each speaker is unique to itself. At 90 db listening level, give or take, with the 1528, other than running most likely in class AB, at higher volume setting, can u even identify the difference in AB vrs A or plainly too many variables. 

@robshaw at 84 dB and also 4 Ohms, the speaker's efficiency is only 81dB. The Fritz is 87dB and 8 Ohms so its efficiency is also 87dB (since the sensitivity measurement is 2.83Volts at one meter, which into 8 Ohm is 1 Watt but into 4 Ohms is 2 Watts). In addition, with less efficient speakers there is a thing called 'thermal compression' that causes a loss of dynamic contrast. 

I think you'll find yourself missing the Fritz in short order!

You cannot hear the transition between A and AB. In fact you've been hearing it all along (since musical peaks take more power than most people think they do) and not been bothered by it now. So no worries in that regard.

However, all amps make more distortion into lower impedances and that distortion, especially when you're asking 4 times as much power, is going to be audible as being harsher, less detailed and likely brighter. That is because the distortion increase includes higher ordered harmonics, which the ear senses as brightness and harshness (this is because the ear uses harmonics to sense tonality which is why you can tell the difference between an acoustic and electric guitar). 

If you want to move forward, pay attention to impedance and the sensitivity of the speaker candidate. Higher sensitivity is better and 8 Ohms will sound better with all amps if other variables with the speaker are rendered equal.  

Thanks all very much. Joseph audio pulsar has been in my sights.(used) Some  people prefer the originals rather than the graphene. I have been intrigued by the Marten Oscars, and the Acora mrb-1. The ATC's always caught my eye, albeit harder to drive. I guess my pass X-250.8 should be fine. Not sure which model would be the best in the room in question. Always been curious about the SCM 19, but, thought it would be similar to the FRITZ. Was thinking about the SCM 50 (used) However, not sure whether it would be too much fro my smallish room? Thoughts??  Thanks Robert

@robshaw 

I have a smallish room too and if you control it properly a floor stander will work fine. I recommend auditioning Rockport speakers. They are superb.  My  Avior ii speakers sound fantastic in my room. Good luck!

I put the Fritz (I’m kinda guessing here based on what I’ve read of them), Joseph Audio, and my Soliloquy speakers in the category of good dynamics and outstanding audiophile characteristics like an expansive 3D soundstage along with pulling off an excellent disappearing act as a sound source.  I’d flip that with ATC speakers as they’re very good with the audiophile stuff but are outstanding in the dynamic realm if that helps put it in perspective (at least as I see/hear it).  My guess is the ATCs would sound more reminiscent of what you experience with your custom Tekton speakers, but that’s just an educated guess on my part FWIW.

For ATC, the 50s might work in your room but could also be a bit much.  I’m confident the SCM 40v2 despite being floorstanders would work as they don’t go all that low and are a sealed design, and you’d still get that magical dedicated dome midrange driver that I really think could be what you’re looking for from what you described with the Tektons (although the 19s certainly share similar characteristics to a lesser degree).  Here’s a pair of 40s here that appear to be discounted, and I don’t see any used at the moment. 

https://www.audiogon.com/listings/lisb901e-atc-scm40-full-range

Sorry to drone on but hope it’s somewhat useful. 

@soix You make perfect sense. Always have liked the SCM 50. Never pulled the trigger. (a lot of money even used)  The SCM 40 (you sent an attachment) always seemed to have good reviews. Still wonder about overpowering the room???  I believe you get my statement with the Tekton Encores. You may have a point. 

In addition, here are the speakers i'm currently exploring,( all used) Marten Parker ,Acora MRB-1, Joseph audio pulsar, 2 Sonus:  Faber Electa Amator 3, Olympia Nova 1, Daniel Hertz Eva, KEF ref meta 1, Possibly QLN-3 a  small tower. scm 40's intrigue me too.  Thanks to all.