Valve Amp for Sonus Faber Sonetto IIIs

I'm looking to move into the enticing but deeply confusing world of valve amplification. The more I read online the more bewildered I become. The SF Sonetto III's that I own are 89db sensitivity and 4ohm nominal impedance and I've seen the suggested amplifier output given as anything from 50W to 250W. Can anyone enlighten me as to realities of the situation. I don't play music at ear-bleeding levels, mostly it's classical--chamber to opera, jazz, and acoustic, although I sometimes get nostalgic for my lost youth and play King Crimson and Jethro Tull.

I'm currently looking at the Sinfonia & Triode amps from Unison Research, the McIntosh MA252, and the Synthesis Roma 510AC. 

Any thoughts or advice (of the idiot's guide variety preferably) others may have will be gratefully received.



At CAF did you happen to come across a brand/company called Angstrom Audio? Another example excellent Italian electronics. I heard their class A Stella integrated amplifier. Very nice and natural.