Feliks, no reason not to try either amp. Personally I use a tube amp on speakers not meant for tube amps, and I'm in heaven every time I listen. You can do it if you're willing to accept tradeoffs. In your case you'll get "tubiness" and liquidity and the imaging that you're probably lusting for. What you'll not get is earth-shattering bass (which isn't in the cards for that Boenicke anyway) and you won't have incisive punchy transients at higher volumes.
Raven Osprey vs Octave 110 with low sensitivity speakers
I’m wondering if anyone out there has experience running the Raven Osprey into low sensitivity speakers. I have a pair of Boenicke W5’s that are some of the most amazingly life-like speakers I auditioned in the hunt, and with breathtaking soundstage—in an amazingly small solid wood cabinet. The price you pay is that these 4 ohm speakers are extremely hard to drive: 83-86 dB sensitivity—and I have them in quite a large, open room. Right now they are driven by a Parasound Halo integrated which does a fantastic job in powering them, but I’m in search of even more resolution and detail, and also did want to give tubes a try. My choices are used Octave V 110 SE vs Raven Osprey. The Octave definitely has the power, but I’m told might not be quite as resolving in the upper registers. The Raven Osprey is a lower power unit, but does have the subwoofer bypass that allows me to take some of the load off of the amp (a digression on Boenicke customer service: Sven Boenicke was kind enough to personally go through my room characteristics and set-up to advise on speaker placement and sub integration—although he seemed a bit sad that I’d risk corrupting his sublime bass characteristics with an outboard!). The Octave is a known, the Raven would be unknown since I can’t audition and would have to deal with the hassle of returning/restock: is it just asking too much of the Osprey to power these little beasts? Is the Octave a no-brainer?