Hi Andre,
I can't help with the knobs. I built a 610 from the schematic that has been floating around here for some time. This is based on the original pre and not the current reissues. I read through the threads here and ended up using a UTC a-25 for the output xformer. Otherwise I copied the circuit exactly and used the power supply from the la2a to power it up.
I've built a bunch of other tube pre's including the G9, one based on a NYD schematic and one from an old RCA tube manual circuit. I've also used a variety of xformers on these projects. I haven't done extensive work with the 610 yet (just too busy at the moment) but I'm very happy with it.
You'll see differing opinions around here about UA gear. If you're looking for a classic tube pre to add 'warmth' to your signal, then you can't go wrong with the original 610.
byron