The volume control is going to be difficult. If you had a larger budget, you could go with something like a Wadia, Cary, Esoteric, or maybe even a McIntosh. I would recommend going with a passive volume because you'll have a lot more options.
I don't know if you would be interested in something like this, but if you could find a good used Sony 9000ES, you can have mods done to it. The Sony can be had for under $400, and you can use the rest for upgrades. Here's a link to an article that goes over this in great detail.
http://vandersteen.com/media/files/APJ%20Files/APJ11_Proof.pdf
I don't know if you would be interested in something like this, but if you could find a good used Sony 9000ES, you can have mods done to it. The Sony can be had for under $400, and you can use the rest for upgrades. Here's a link to an article that goes over this in great detail.
http://vandersteen.com/media/files/APJ%20Files/APJ11_Proof.pdf