Help Tannoy XT6F with Primaluna


Hello all.
Just got a pair of Tannoy Revolution XT6F speakers. They are supposed to replace KEF LS50s. I'm driving them with a Primaluna Prologue Premium power amp. The new Tannoys sound awful with the Primaluna. Very peaky upper midrange and not much bass. Pretty unlistenable. Tried them with my old Rotel RB990 solid state power amp and they sound much much better. Tried the 4 and 8 ohm taps. Tried the stock Primaluna tubes and some KT 150s. No good. The Primaluna sounds great with the KEFs. Any ideas? Thanks in advance.
Ben
honashagen
Update.
I got another 125 hours of burn in on the Tannoys for a total of about 200. Sounding better. Another 200 should do it. 

If your morrows are also brand new, then that's a major cause of sound oddities.  The Morrow cables absolutely REQUIRE around 400 hours of break in.  

The Morrow site explains this in great detail, they are not like most other brands since they have mainly solid core copper plated with silver.   I've got 3 pairs of Morrow RCA's and experienced this myself.  I decided against buying Morrow speaker cables for this reason.  I had left my system alone for about a month, and the Morrow cables needed an hour to get back to normal.  
Sold the Tannoys and the Primaluna. Tried the XT8Fs. Awesome speaker. If have since moved on to a pair of Dynaudio Contour 3.4s.
Cheers!

 The Prima Luna Dialogue HP
will drive anything. 6 signal tubes  and 8 power tubes 4 a channel you even put in KT150's.  

Musical and built with no apologies.


Sorry to revive such an old post,
anyone have anymore experience with these speakers? And if so what are you driving them with?