I know you guys have heard me say it a million times. The RT series sounds AWESOME on tubes. My RT fetish started after hearing my first pair of RT speakers. So far I've heard the RT5, RT800i and now the RT15i on my gear.
I just received my pair of 15i from Beardog today and have them playing on my Dyna. They're all similar on tubes. The sound just floats around the room and the speakers dissapear. I love it.
I've yet to hear the new RTi in my system. I'm not a fan of their new tweeters.
So all you tube heads, if you have a pair of RT speakers laying around, give them a run on your gear. Very fun speakers.