How many tube watts for Vandersteen 2's?

I don't believe that light loading the RM10 would reap any benefit while driving the 2ce either, particularly if it sounds better from the 8 ohm tap.
The choice of tap may very well be speaker dependent however,the 8 omh tap has been the definative choice with each and every speaker speaker I have paired it with.
Tannoy Westminsters, Merlin VSM,proac 2.5, and a pair of vintage quad 57's.

Hi Pabul57. I am not sure about Rogers comments with regards light loading however,it is impossible to ascertain with any certainty which tap is appropriate to use as no loudspeaker represents an unchanging impedance at all frequencies.
The 8 ohm tap typically match loads between 4 and 8 ohms, the 4 ohm tap will be a better match for impedances that fall below 4 ohms.

The one thing that I am more than certain of..... The 8 ohm tap is far and away the right impedance choice for the Merlin.