Audio Research SP16 vs SP3A1 and SP3C

Anyone ever compare an ARC SP16 (phone and line stages) vs. a SP3A1? (and/or a SP3C). If you have heard both (or all 3) please let us know what sonic differences you heard. Thanks!
The advantage of the SP-3A1 and SP3C are of course the tone controls if you require them. Hands down the SP-3C sounds superior to the SP-3A1 in tonality as well as quietness, detail etc. Basically there was no downside to the power supply update. The SP-16 sonically represents more closely current production ARC product. I have not heard the SP-16 side by side with the SP-3C. I own an SP-3C and won't sell it. I love it. It is a bit more tube like and a bit more romantic and probably not as quiet as the SP-16. And of course, the SP-3C has no remote.
Thanks - any chance you can describe in more detail the tonality and other differences (and any similarities) between the 3A1 and 3C? In the highs, mids, low end? Did you own the 3A1 (for how long?) and then have it updated? What speakers and amp and source do you use? Thanks again