The recent Audio Research preamps with phono are the GS Pre, SP20 and the SP17. The SP20 is basically a LS27 with phono stage and different styling. As I said before the sound is more modern and detailed with a larger more 3D soundstage. They don't have that "classic" tube sound.
The SP10 is more romantic and sweet sounding. But less detailed. It has a following and can be pricey. It is also very dated. It was very good in it's day. But preamps have come a long way in the last 30 years. Far more then amps. I owned both an SP8 and a SP9 mk2 many years ago. I much prefer the more modern sounding preamps.
I know the Ref Phono 2 and Ref Phono 2se have 2 inputs so that they can handle 2 arms. That is probably my next upgrade.
As I said I own a Ref 5se. While not cheap, this is an incredible preamp. I have owned quite a few preamps and heard many more. There are few that sound as good even at over twice the price. Both the SP20 and LS27 don't even come close.