How many tube watts for Vandersteen 2's?

I have the Vandersteen 2CE Signature II and I was driving it with the NAD 2100 that are set to Bridge (mono) at 300wpc. The sound is awesome and I love it. BUT, when change the NAD to my old McIntosh 2100 rated at 105wpc in stereo mode, the sound became more alive as in the low bass is a lot fatter and more natural and cleaner mids and highs. But if I or you guys can get a tube amp, it will even sound better I mean a lot better.

Full day of listening to my newly acquired RM-10. I had it light loaded on the 4ohm tap for the 7ohm rated 2ce sigs. After 4 hours like that and being rather unimpressed by the sound I was getting, I used the 8ohm tap. Far superior in my set up. Sound opened up and more dynamic. I'm not drawing any conclusions obviously but I'm not too anxious to go back to the 4ohm setting either. With my LSA passive preamp at 2-3 o'clock the amp had plenty of juice for the Vandersteens in my sizeable room. The bass is surprisingly tight and full. Any edginess and brightness that I used to have with my ss amp is pretty much gone.

Maybe it was breaking in? I would try the 4ohm tap one more time after it has broken in for a while and you use to the sound of the amp. I'm curious what you think then. A great little amp - isn't it?

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.

Ecclectique, any idea why that would be given Roger's comments on the benefits of "light loading"?