Audio Research Preamp Experts?

So you feel the LS25 or 26 (The ones below the REF series), is better than the line stages from the earlier years? Like LS5s or SP10 or 11s etc. Is there pretty much consensus on the idea that ARC has simply improved over time? Is the LS25KI an improvement over the LS22? Feelings about those two? I understand that many prefer the LS25MKI over the MII (6922 to 6H30?)

How would the line stage in the SP-3c compare to the aforementioned "favorites" ??

Can you clarify also what would be considered a worthwhile upgrade from sp16 and why?

Thanks.

Minor1, SP-15 is different, no tubes in the line stage.

SP-11 MKII is the better choice.

The LS-5's are extremely high-value preamps, particularly if your system is balanced.

The LS-3 is one of the great "cheap" preamps available used, especially, as the above poster notes, if it is used through its direct input. Me and my dealer preferred it to the LS-2b. I bought one fifteen years ago and while it's been out of my system for many years now, I pull it out every now and again - it sounds really good for a moderately priced preamp, and is one of the very few moderately priced solid-state preamps that sounds really good.