Deal or no deal, 10k is a lot of money for a phono stage. If I couldn't arrange for an in home demo, I wouldn't even consider it. Its not something you can flip and break even on if you don't like it. An authorized ARC dealer is able to sell if for top dollar. Since you're not a dealer, its highly unlikely that you'll be able to get that much in a private sale.
Looking at your system, I would take a different approach to this. If you buy the ARC, it will outclass your DV-20 by a wide margin. Its a great cart, and I have one myself. But its the low output version. If you don't get a new cart, as well, you won't be taking advantage of what the Ref 2 is capable of. So now, you'll be compelled to go through with another expensive upgrade. Why not split your budget and get a new cart and a new phono preamp? 8-10k is a serious budget. You can get an exceptional combo for that kind of money. It looks like you want tubes, so you may want to check out an Aesthetix Rhea, and match it to a good cart. Aesthetix is a great match for Ayre and Vandersteen. There's other good phono stages as well, but that would be my first choice.
Looking at your system, I would take a different approach to this. If you buy the ARC, it will outclass your DV-20 by a wide margin. Its a great cart, and I have one myself. But its the low output version. If you don't get a new cart, as well, you won't be taking advantage of what the Ref 2 is capable of. So now, you'll be compelled to go through with another expensive upgrade. Why not split your budget and get a new cart and a new phono preamp? 8-10k is a serious budget. You can get an exceptional combo for that kind of money. It looks like you want tubes, so you may want to check out an Aesthetix Rhea, and match it to a good cart. Aesthetix is a great match for Ayre and Vandersteen. There's other good phono stages as well, but that would be my first choice.