Spendor D9.2 Run In

I wonder if you possibly have bad tubes in your MC275.

Spendor has made some duds with respect to tweeters but has never failed to get the midrange right. You might try to borrow a SS integrated from a friend just to rule out the amplification. 
 

The D series speakers measure nearly ruled-flat and as a result will sound “lean” compared to many/most competitors. 

Make sure your source material is good.

internet radio etc can vary a lot 

I had the D7 for a while and the mids were pronounced but I wouldn't have used the word blare. The tweeter was a bit annunciated in the presence region. Any comparisons to the Volti's? 

The Spendor midrange is as overly pronounced as the Volti's was not.  I have switched the Spendors between my SS and tube Mac gear and really don;t see much difference.  "Lean" is a good word, but the pitch seems wrong to me.  t is true some recording sound better than others.