What Sensitivity with Tube Components?

I think almarg is giving you some good advice. I have been using low-medium powered tube amps for 40 years, and if you want to get into tube amps, I would not say anything to discourage it, they can provide a very satisfying listening experience. My advice is not to get too hung up on speaker sensitivity. The key is to mate them with speakers that have a fairly benign impedance in the 6-10 ohm category. For instance, the original Pro Ac Reponse 2 had a sensitivity of only about 85 db, but they worked nicely with a 50-watt Audio Research tube amp that I had at the time, because the Pro Ac impedance was perfect for the amplifier. On the other hand, there are speakers out there rated at 91 db sensitivity, but the impedance is 4 ohms or less and would not mate well with most tube amps. I'm not sure about the impedance rating of your current speakers, but that would be the place to start.

  Perhaps I will try a true bi-wire set up with the switch set to low. Worth a try.

Hi wcc10 according to yamaha amp manual this is what has to happen to test that feature setting.  Even Yamaha recognizes different speaker impedance's and it is the reason they included that feature in your SS amp. Give it a try - costs nothing.  

from that earlier link.

the R-S700 is bi-wire ready. In this case, it uses both sets of internal amplifiers (Speakers A & B) for one pair of bi-wired speakers. This implies a true bi-wired scenario, where separate discrete amplifiers are used for the tweeter/mid-range and woofer section of your bi-wire-able speakers.

 
So give it a try definitely. 

But and this is a big but..... someone that is used to a 12 inch woofer like yourself - it can be like mothers milk you know ...  if infants could talk when being switched from mothers milk to artificial I am sure they would say - ew ,  yucky, phewy.

If the above doesn't work I would switch speakers, or get your wife to approve a sub to bring balance to the music.Those speakers in a space surrounded by windows is a challenge.

Let us know how you make out - good luck 


     

Mother's milk! I love it! ;-)
All very good info. I'm glad I posted this question on this forum.
I have another set of 12 ga cables so I will give the bi-wire a try. As said, it cost's nothing! I'll let you all know how it works out.

Thank you all!

wcc10,
You have received some very good responses here. Al gave you the definitive answer,= your speaker is designed to be driven by a transistor amplifier. Small, inefficient and striving to produce bass(via low impedance). I'm a tube guy but tubes  usually won't match well with this type of speaker design. As has been said, tubes work better with higher impedances with a relatively flat impedance range. If you ever decide to try a tube power amplifier, get speakers with friendly  and flat  impedances. With your speakers, stick with solid state amplifiers.
Charles,

Yup, that is the message I'm getting. Makes total sense and I'm glad I posted before I took the plunge into tube amplification. I've had these B&W speakers for about 1 year and I always intended to "upgrade" at some point. This discussion has shown me that upgrading my speakers with a view toward going over to tube amplification requires serious homework before making that switch. It also shows me that where I buy is as important as what I buy. If the guy selling me the gear has no clue about what he is selling then chances are I will end up not being happy.
Mcintosh MC275 MK6 - B&W CM6 S2 don't match up very well as proved to me first hand.

An update; I did try the Bi-Wire set up with my speakers & Amp. With the Impedance switch set to Low and using two sets of 12 GA cables there was a bit more "oomph" but also seemed to be a bit of distortion again in mid-range. Switching back to impedance setting High cleaned up the distortion and sounded more like the cables single end at the amp and Bi-Wire at the speakers. I was using two different brand of cables so that must be taken into consideration but I could not justify using 2 cables as there was not a great deal of improvement. Speaker placement is highly important and I guess right now I'm going to have to be satisfied with what I have. Which is not all that bad considering.
Thanks to all for the help!