Hi Ross;
I wrote you what I thought was a thorough reply yesterday morning and Audiogon decided my shipping address was "unverified" even though I go to work there most days for years (!) I got them to manually "verify" me. Ugh! so....
I note that you can replace minor electronic part yourself so that adds a big savings to your side of the ledger.
Here is my experience with ARC preamps:
ARC gear is like buying a 80s Ferrari- not that expensive to buy but very expensive to own.
ARC's SP 10 and 15 are fantastic preamps for cheap (2500-3500) but thy are now old and the original caps are going to fail on you. Caps are cheap direct from ARC so if you have a chance to buy one of these greats that doesn't work for $1,000 you have a bug % chance it's just a power supply cap and you are under $30 from a working unit. A little poking around with a multimeter will tell you if the uF is OF on the others. There is a lot of room on the chassis to get in there and swap out weaker parts. Plus it's a lot of fun of you like that kind of tinkering.
The highest rated Ref gear in the mind of the ARC employees I know is the Ref 5 and the LS 27. Those are not preamps I've owned but I'm advised they are the "best value per note" in the modern lineup by my ARC mole.
ARC had a bad spell in the 90s as Bill Johnson farmed out a number of the iterations following the SP 15 to "lesser mortals" there at ARC. The ARC insiders considered them "gimickey" and not really worthy of the logo. Their aftermarket value reflects this.
Your VS110 is a great little amp and will play nicely with an ARC preamp. ARC products are designed to compliment one another so you won't have a great % chance of a non-ARC preamp fighting with your AS110.
The SP 10 on eBay right now looks pretty good and is well bought under $3000. Tubes for SP 10s are not insanely expensive at this time either. I'd re-tube the entire unit if it was my turn to buy one. ARC thinks 1500 hours is about when you need to consider re-tubing and 2000 hour tubes are rapidly loosing their dynamic capabilities. again- like owning a Ferrari :)
If you have a chance to audition a few "vintage" ARC preamps I'd make every effort to do so before you buy one.