Which Audio Research Preamp?

I currently have an Audio Research SP-9 MKII driving an Audio Research Classic 60 which in turn drive Vandersteen 2Ci's. I've been thinking of upgrading the preamp and have favored an Audio Research preamp, preferably one with a phono section. After reading many reviews and watching the classifieds on Audiogon there are a couple that are full featured and worth considering, the SP-14 and SP-15 and quite a few that are just a line stage (and require me to buy a phono preamp); the LS-5, LS-15, LS-16, LS-22, to name a few of the newer models in my price range. The question is are all these worth serious consideration and would they be a significant improvement over the SP-9? If anyone has recommendation for other brands that work well with the Classic 60 I'd be interested in hearing those too. Thanks!
A friend of mine just bought an SP-9 Mk. II. He made three mods to it -- put in an IEC plug and oil caps and shielded the tubes. He said the IEC with a better power cord was by far the most significant improvement. It's a relatively cheap mod to see if there's any reason to upgrade.
Why would you want to upgrade to SP-9 it's a very fantastic sounding preamp with and excellet phono section.
THe SP9 is a very nice preamp

I own the LS 5 which is all balanced ins but is a spectacular preamp - more open than the ref-1
a very musical piece - light years above the LS2 I had before

an LS 15 16 or 22 is a lateral move, you are not really gaining anything

You might consider a Steve Huntley upgrade to your sp9
Steve worked for Audio Research, Wadia and Cal Labs as a designer, and makes significant upgrades to the pieces using the latest electronics and knows where each units limitations were. He has several levels of upgrades for specific Arc pieces and is very knowledgeable and straight forward. I'll be sending him my preamp.


do a search on gns here at audiogon, my friend has an LS22 and it really opened it up