OK I took a few more voltage readings:
Switch position 3
Tesla RD27AS 2.9V, 3V, 1.0 and1.1 Ohm filament target 4V
Osram PX25 3.28V, 3.29V, 1.2 and 1.5 Ohm filament target 4V
Switch position 2
EML GM 45 2.29V, 2.27V, 0.5 and 0.6 Ohm filament target 2.5V
BUT my DAC has a filament trim pot which you can use to optimise for a particular valve.
http://www.lyrima.co.uk/dhtreg/dhtRegIntro.html
and details here:
http://lyrima.co.uk/pdf/Assembly-V7-2-RX.pdf
So whilst you can swap valves around with an approximate voltage setting, you can OPTIMISE to a precise voltage for your favourite valve. Or at least a voltage that makes the friggin' thing work properly, LOL.
I will adjust it for RD27AS soon and see if I get a better result as I am curious why people seem to like it more than I do. I am a full volt too low on it.
If ever there was a case of RTFM...
For strangers these switch positions do NOT equate to a Lampizator and nor does the trim pot (AFAIK but it might - does anyone know?).