Good move!!
I have been very happy with my ARC gear. I recently decided to move from a SS pre (McCormack RLD-1) to a tubed pre and since I have an ARC amp I naturally auditioned the ARC preamp offerings. I nailed it down to SP16 ($2500 new) vs. LS25 ($5500 new). Big diff, yeah, but I could have grabbed a LS25 for about $4400 as it was a CES demo. I listened for hours and came to the conclusion I actually preferred the SP16. Shocking to me, as I do believe this is the first time I've picked the *cheapest* piece of gear I was auditioning
What it boiled down to was the SP16 appealed to my heart and the LS25 appealed to my head. The LS25 was very impressive, very hifi. The SP16 made me want to listen to disc after disc... Now the SP16 had some shortcomings, notably that the images were fuzzier and less distinct, the soundstaging wasn't as vast, and it wasn't as detailed or as transparent. In the end I decided not to buy either and to keep looking.
Then a perfect, as-new SP16 with phono fell on my lap for the silly price of $1300. OK, I'll play with that for awhile.
I've had it for about a month now, and after tube rolling a gazillion 12AX7s I have found this pre to be nothing short of EXCELLENT and a true bargain in hifi. Want better soundstaging and more distinct images, like the LS25? Drop in some Ei Elites, Telefunkens, or some 50s Mullards... Want a romantic, lush sound? Leave the stock EH's in, or roll in some 70s Mullards. Want clear as a bell? Telefunken.
In short, you can play up the strengths and reinforce the weaknesses quite easily. It will always be more tubey sounding than the LS25, but in my book this is a GOOD thing.
Others to look at are CJ, as mentioned, and I think Rogue is worth a look as well. I haven't had much experience outside of a recent listening, but I was intrigued. And it's well-priced, too.