What Sensitivity with Tube Components?

I agree with yogiboy - it's the speakers that are bright. As far as power I drove Dynaudio C1's with 40-70-110W Octave tube integreted's with no problem. BTW the C1's are rated at 85db. What I did notice is with each 'bump' up with power there was a hair more control in the music.

The room with glass walls on both sides contributes to the brightness.

Yes, the speakers are on the rubber feet supplied with speakers. I was afraid that the answer lay in the speakers themselves. It is unfortunate that today you can spend $2,000.00 on speakers and not be satisfied. Sure, in the total these are inexpensive speakers and maybe I expect too much?
I go back to 12 inch woofers in my old AR3a's. Apples to oranges I know.

I would not try to cure the brightness by going to a tube amp.  Somewhat counter-intuitively, it would stand a very good chance of worsening the brightness.  The reason is that relatively small speakers such as yours, that strive for good bass extension relative to their size, are often designed with a lower impedance in the bass region than at higher frequencies.  The idea being to capitalize on the fact that a solid state amp will deliver proportionately more power into low impedances than into higher impedances (assuming the amp is operated within its capabilities), thereby enhancing the speaker’s deep bass response.  A tube amp will not perform in that manner, and depending on a number of variables specific to the particular tube amp and speakers, and also on which output tap is used, will very often deliver even less power into a lower impedance than into a higher impedance, resulting in an overly bright sound with a speaker designed in that manner.

I couldn’t find an impedance vs. frequency curve for your particular speakers, but that is one of the reasons that many B&W speakers are not considered to be tube friendly.

Good luck.  Regards,
-- Al

It is unfortunate that today you can spend $2,000.00 on speakers and not be satisfied.

Sure, in the total these are inexpensive speakers and maybe I expect too much?

wcc010 - imo - Those are not inexpensive speakers. And they definitely will not replace what a 12" woofer will do.

I am curious to know what happened when you switched to the low impedance speaker setting on your amp ?  Did it change anything? 

Cheers