Anybody Felt Lower-End ARC preamps Bass-Shy?

I would suggest for more pure sound to use the single ended outs from your preamp for the sub and use the balanced outs to your amp. Let the mains run full range. This will take the extra electronis from the crossover out of the mains which should give a much richer sound.

Have you checked if the output impedence of the preamp e.g 100 Ohms is compatible to the input impedence of the power amp e.g 20 KOhms? Anything less than 200 (20000/100) can mean bass will suffer. ARC will normally state the minimum input impedence of power amps necessary for its preamps.

I'm not familiar with the mentioned Metheny discs. But being "earlier" works, as you say, is it possible these records are just lacking the ultimate bass?

You may want to try running some sort of a reference cd, may be even stereophile test cd 1 or 2 with bass frequency test tones.
Or may be get a cd with plenty of bass. I recommend Brian Bromberg "Wood II" cd that I often use for bass test and actually enjoy listening. In case you are not familiar with Bromberg, he plays acoustic double-bass and the recording quality on "Wood II" is very good.

It is possible that the earlier Metheny's discs are lacking in ultimate bass but most of my favourite tunes are in these albums. I have a few reference cd's such as "missouri sky" by Metheny/Haden, quite good bass but music wasn't as good as the earlier ones. I've read about Brian Bromberg in another thread and will look into getting his album later.

I've checked the LS-16's specs.
Input impedance is 150k ohms balanced, 75k ohms SE.
Output impedance 600 ohms balanced 300 ohms SE, 40k ohms minimum load.
Input impedance on the Plinius SA-100Mk1 is 47k ohms. Mk3 may be not too far off. I guess it's okay?

Rwwear, I've tried running the mains full-range before but the Plinius was struggling to drive these speakers. I was switching back and forth between full-range and high-pass and found that dynamics was greatly reduced when running the speakers full-range. The rhythm and drive were missing even at low to moderate volumes. I then realized my amp was underpowered in driving these speakers and by high-passing them the load on the amp was considerably reduced resulting in a more dynamic sound.

I think I'll just get another Plinius power amp and run in monoblocs since I need the watts anyway. Then I can run my speakers full-range without losing drive and dynamics and just let the subwoofer fill in the low bass. Another option worth considering.

After reading the responses from the other thread "Mono blocks are better or Stereo power amp?", most likely I'll be getting another Plinius amp and run in monoblocks.

Thanks all.