Here is one that is getting terrific reviews and is not expensive....
Thanks a lot. Your longbow has hit a juicy target!
The other option I'm looking at is a QES Labs HPBA-2. They make units to order and I've enquired if they could provide one without any volume control - that is done by the Vaughan and would only add unnecessary expense and complication to the amp. Similar to the Schiit it is a balanced only effort.
Wise after the event, but in buying the Vaughan, I'm paying for a lot of features I'll never use, particularly all the sophisticated USB input processing. That said it is an exceptional DAC but is not quite doing what I imagined in that it is not also a balanced headphone amplifier.