Newbie Can't Decide Which Tube Amp

I agree with Ralph at atmosphere, But if you insist keeping your speakers, look at the Tsakadiris apollon mono block tube amps, they are right on your budget.I own this monos, they run my Andra hard to drive Speaker without a sweat, with musicality attach to it.

@ckenr,
It appears at least 2 different Concerto models existed, each had different drivers in them. The later model has a diffraction device on the tweeter as one indicator, and look closely at the woofers. This original model reviewed way back was rated at 86/db at 8ohms, and yet the other version showed 88db at 6ohms. Old review here, https://www.technologyfactory.com/reviews/SonusFaber/concerto_stereophile.pdf

Agree, its likely going to take a capable amplifier (tube or SS) for these speakers to get proper performance out of them - as your tech and others have already noted. The Tech Factory review above noted these like a clean 100w amp, capable of peaks up to 250w; betting that was a solid state amp too. I like and use tube amps, and in this case, if I kept the Concertos, it would mostly likely be paired with a really nice sounding solid state amp. You could find a number of nice integrated solid state amps in your noted price range. Or, if you must go tube, maybe others speakers as many here suggested.

Is there a label on the back indicating 6 or 8 ohms? Does it have the smaller soft dome tweeter or the version with the diffraction 3-point star diffraction device on the front of the tweeters?

@yogiboy
The OP is not looking for an integrated amp. No Raven today

really? https://www.ravenaudio.com/product/shadow-mk2/

not to bright are you.

Just buy a Raven 

Actually skypunk, not sure why you are so gung ho on giving free advertising for a couple of guys who went out of their way to read you the riot act.