Audio Research Ref-1 vs sp10 mkII preamp

Curious if anyone has an opinion between the arc ref-1 and the sp10 mkII - sonically, that is. assume the sp10 has new tubes, upgraded caps, etc. how does its line stage compare with the much newer ref-1? i've seen highly modified sp10s for around the price of a used ref-1. i'm interested in buying one or the other. any help?
thanks in advance.
The sp10 mk2 is so good you cannot belive the magic of the project given to the audio community by the late Mr Johnson.
Needless to say, heavy mods are required: ps changed from electrolytics to full polyprops, this mod requires lifting of the entire ps chassis.
All capacitors in the conrol unit changed with Vcaps teflon reference, or V oil, pf values to audionote, volume pot changed tkd stepped top model, all resistors changed with vichay nudes/caddoks tfts/mills/kiwames..power cord changed to Vandenhul, plug from Chris Venhaus, rca females wbt, internal wiring vandenhul mcs 1000 doubled.
Photocouplers entirely bypassed, meaning you must switch the preamp on before the power amps and wait circa 4 minutes.Transistor amps not recommended......
hear to belive...ooops forgot..all tube sockets changed, fitted with siemens and telefunken NOS.
All soldering wonder solder signature.
Only active parts in the preamp are on off switch and volume control.
Cheers, its pure heaven....cartridge output must be no less then 1.6, no covers, two paps vents.
Yep, I had one as well, back in the day, and kept it a long, long time. Very
musical. I had ARC do various updates and upgrades to it over the years.
Biggest issue was microphonics (and as I recall), making sure the phono
section tubes were quiet and well-behaved.

With a smallish ARC tube amp and Crosby Quads, the thing sang.
It finally proved to be a little too noisy to work with my horn-based system,
which requires absolute quietude among the components. But, for a system
that isn't quite so sensitive to component noise, I would probably still make
beautiful music if it were thoroughly gone over. (That thing is pretty darn old
I replaced mine with a Lamm L2, which, superficially, resembled the SP-10.
Both of those pieces- SP-10 mk ii and Lamm L2 now with other presumably
happy owners, but great pieces. And John is right, the magic of the SP-10
was its phonostage.
EAT cool dampers are a must, especially on v1 v2 v9 v10
I was very lucky in the late 80s, bought a truck load of telefunkens and Siemens in holland for cheap; at the time everyone was wasting time going digital.
I enjoy zero noise, 0 microphonics today.
I do admit its a set up extremely hard to manage and achieve for the everyday audiophile. Every single solder joint has been taken care of, and in critical areas hard wiring is a must.
It took me over 20 years to get it right.
You also need a dedicated power supply in the house, feeding itself directly from the entry mains (Vandenhul cable carrying the current).
Similar story goes for my power amps (d115mk2 one per channel vertical biamp). All caps changed, internal wiring, additional outboard power caps, wbt connectors, gain attenuators bypassed (the ones in the back)all GE power tubes and driver.