I know Al may give me noogies for asking (given the price difference).Yup :-)
The only way it would make any sense to spend $26K for pre + power amplification to drive $2K/pair speakers would be if you envision ultimately upgrading the speakers to much more expensive floorstanders, or expensive monitors + stands.
That said, although I have no particular familiarity with Gallo speakers, based on their description I suspect those ARC components would do reasonably well with them sonically. I'd be cautious, however, about mating the Strada with most other tube amplifiers.
Due in part to their unusual crossoverless design, the impedance of those speakers, as shown in the first graph here for the original Strada, varies very widely as a function of frequency, and reaches difficult combinations of low magnitudes and significantly capacitive phase angles at some frequencies in the bass region. Given my strong suspicion that the speakers are designed with the expectation that they are likely to be driven with solid state amplification, the relatively high output impedance of most tube amplifiers is likely to interact with those impedance variations such that unintended tonal balances would result. Those effects will be fairly minimal in the case of the Ref 150, though, because (as with some other ARC amps) it has significantly lower output impedance than many other tube amps.
My one other comment is that you'll almost certainly need a sub (or two) with those speakers, given that their frequency response is specified as "68Hz - 20Khz +/- 3dB (in room with boundary reinforcement, speakers within 1 foot of wall)."
Regards,
-- Al