Esoteric S-05 compared to the Esoteric F-03a

Hello, 

Has anyone compared the two subjects - or at least your observations of the F-03a compared to other amps?

I've had many amps - including: Luxman 590axii, Moon 600i, Audio Research Ref 75, and more - so any notes and comparisons would likely be helpful.

Context: I have had the Esoteric S-05 (30-watt amplifier) previously, and I was extremely impressed. I got an amazing deal on it and unfortunately I let it go to fund other priorities. I likely won't be able to afford anything close to the MSRP ($12,500) again, and there are very few on used market as it's so new.  I believe I can get the F-03a for closer to half that price.  One last note: I ran the S-05 w/out a pre-amp, Lumin LEED volume control direct to amp)

Has anyone been able to compare or listen to both and what were your observations?

Lastly, I hope this will at least get some more conversation out there on these amazing pieces - really can't find much at all on the S-05. 

Thanks!