6550 and KT88 differences?


Can someone describe the tonal differences to me?

I'll be using it with a Primaluna Dialogue integrated amp.
gnugear
I have ASL Hurricans which use KT 88's. Has anyone (or can this be) changes tubes to 6550's...and what was the differnence with the Hurricanes (sound).
Any good prices on KT88?
The SED 6550 had a very soft and rich midrange, almost mid hall sounding, not clinical sounding though. It made voices just a little too soft to let singers with an etched voice like Diana Krall sound natural in my system.

The SED KT88s much more dynamic and open sounding, yet still possessed a textured midrange. If you have a bright amp that is bothering you, you might like the SED 6550, if you want to open things up and be more front row center sounding, the KT88s will probably prove to be the best choice. The KT88 for me was the much better of the two choices in tubeds.
I have a pair of Hurricanes and I use them with a new set of Chinese KT-88 tubes.
I was offered at a great price matched sets of new Ruby,A-R 6550 tubes with the VTL logo printed on (they were made for the VTL amps by the RUBY corporation) on the tube itself is the VTL logo and on the other side the number:
6550
A
USA
Those tubes look far better made than the Chinese KT-88's
Are they made in the USA and would they sound better than the KT-88 ?