Wilson Audio Sasha 2 vs Sophia 3

George,

Thanks for the link. I did read that review.  I've also ready so many comments about how well the Sashas play with Ref75, but perhaps I should consider the Ref150.  I did notice a huge dip ~2ohms creating a very significant gap/phase angle from ~100hz and for quite some time up the audio band.   I'll keep you all posted on how they sound. 
Thanks again for all the input. 

I have Sasha 1 with Ref 150 ( KT 150 tubes). No problems driving the Sashas. Back when I had the Ref 110 amp, I brought the Ref 210 monos in house to see how much better they would do with the Sashas. At the time, it was about 10% (mainly in dimensionality and imaging) with no appreciable difference in the low end.
Based on that, I’ve always felt the 150 WPC amp is best bang for the buck with the Sashas. That said, I’ve never heard the Ref 75se with Sashas although I’ve heard the Ref 75se vs the GS 150 with the Alexias. It was no contest. The GS 150 drove the Alexias very well in all respects while the Ref 75SE drove them in a merely satisfactory way. Hope this helps.

No problems driving the Sashas. Back when I had the Ref 110 amp

Yes, but the Ref110 has double the amount of output tubes than the Ref75, 8 instead of 4.

The Ref 75 may sound fine, even in the bass/upper bass to the unwary, but when an amp with current is compared to it, then one will hear what it's not doing right in the bass/upper bass.

Cheers George 

How can you really tell how much current an amp has.  All that is published is the watts, typically.  I know "not all watts are the same" - which I've always interpreted as some have more current/guts than others...  Can anyone point me to a layman explanation AND a way to tell how much current a given amp has?  Thanks!

"Typically" an amp that is solid state with big power supply and using bi-polar output transistors (BJT) are the ones that will give the best current output.
To put that into laymans terms, an amp that can "almost" double it’s wattage for each halving of speaker impedance load is a good current deliverer.
Look at the specs.
EG:
50w -8ohms
100w-4ohms
200w-2ohms

For instance very sought after huge old massive Mark Levinson ML2 monoblocks don’t have many watts into 8ohms but they do
25w-8ohms
50w-4ohms
100w-2ohms
200w-1ohm.
https://c05d22d421713559ae3382d5a980815d4cf5ca6a.googledrive.com/host/0B_s-XMmdi448RDhFR2hhdXVQRWM/Mark-Levinson-ML-2-Mono-Power-Amplifiers-.html

Tubes and mosfet amps, don't do these sort of currents, that why they don't usually advertise it. 
Cheers George