RGA,
why not go for a kit2 with preamp kit.
I know that the dealer advised against a preamp, but probably means he is against using a pre with the A48b. Plus the kit2 with preamp kit are both tube so it should be ok.
The 2 units will run you 1700US (probably a notch less after negotiation) Plus you can sell off your Sugden for a little bit. Save 7% on taxes, which is another 150 or so. So at the end you are looking at about the same as the soro.

Good thing is that you can easily upgrade it when you get more cash. If you are uncomfortable with kit building, I can help you build it if you would like and if you can trust me of course. Light electronics is sort of a hobby for me anyways.