need an extra preamp out

i recently purchased a VTL Ultimate Preamp. The version I got has only a single set of outputs. i plan to connect these to my monoblocks but i would also like to connect my subwoofer to another set of outputs if possible. i know i can get a y adapter but i would prefer to have a dedicated set of outputs for each. is it possible to convert (with the help of a good technician) one of the unused input RCAs to an output. please advise.
No, no conversion necessary, leave those inputs alone. A good tech could add RCA's out if he found the room. If not he could still find other ways to add RCA's out.
It may be possible to convert an unused input, but I wouldn't. I would just use a y adapter, or better still connect the sub to the speakers using high level inputs if your sub has them. I prefer this connection.
i would either punch new ones to the available chassis space(can even use side pannels) or use Y-cable. Reconnecting to the input will make your unit substantilly less marketable if you want to change/upgrade it.
Instead of a Y-cable, I'd go with one of the solid metal RCA splitters.
Send it to VTL for additional outputs or connect subwoofer to speaker level if you have that capability.

You should believe me that last thing You want to do is to pay 2-way shipping of VTL to WestCoast from EastCoast.
As far as VTL tech personnel goes, ordinary local tech can do same job or even better meaning they're not brilliant at all including Luke himself.

There are tube repair services offered at most of the music instrument stores including Guitar Center... Most of Guitar Center techies will immediately recognize most of guitar amps in VTL equipment. They can modify and/or troubleshoot quick, cheap and shipping-free. As you may all know that our high-performance tube equipment isn't much different from guitar amps

No need to re-invent bicycle seriously.