Ok, kind of an experiment then. Of course we can't predict what kind of sound qualities others will like, so I would take this on from a different angle - what's the most "tube'ish sound" you could try, which would best show off the tube qualities? What experiment will give you the greatest insight into how tubes differ from transistor amps? Then, if you don't like that, there wouldn't be much sense going forward with it. You would have heard the example of "good tubes" clearly.
To that end, I would begin with Single-Ended Pentode (SEP) amps that feature no feedback. I think they offer the best window into tubes that you can buy on a modest budget. The most common recommendation, and one I used to make all the time, is the old Dynaco Ultralinear amps, like the ST70, MKIII and SCA35. But, ultralinear amps aren't really that close to today's state of the art in tube amps. Yes, they are good, and yes you can get lots of watts per dollar, but watts per dollar isn't the best way to show the strength of tube amps. A classic Single-Ended Triode (SET) amp would probably cost more than some of the new SEPs, and so for that reason they would be my second recommendation if you can find one in your budget.
A typical SEP with no feedback and really good transformer and caps inside, will demonstrate the beauty of tubes very well. The fine grain, the exquisite detail, the openness and see through clarity is common to these amps. You compare this to your SS amp, and you will say, "Oh, now I get what this tube thing is all about." It will be very obvious.
The Dynaco and all the hundreds of "ultralinear clones" fall behind the SET, SEP, in the finer points of tube sound, but they do offer more power. And to be clear, "more power" was the exact driving force behind the design of the ultralinear amps. On acoustic suspension speakers, the ultralinear has a clear advantage over SET/SEP. The cool thing about horns is that it opened the door to these better sounding, but less powerful designs, like SET/SEP.
Thanks for the recommendations however it's full steam ahead with the ST70, yes, there is a winner of the two.
I decided to get Bob L's advice and much to my surprise, he said I should go with the lower priced ST70.
Sadly, they do not keep wired boxes in stock, it will take up to 3 weeks from the payment date.
I am SO excited, my very first tube amp! Perhaps down the road I'll give SET amps a shot who knows.
I'll post pictures and my thoughts later on.
Thanks again to everyone!
Congrats on your purchase!
I may have missed it but did you give any thoughts to what pre you'll be using?