Ascend Acoustics Sierra-1s VS ACI Sapphire XLs

I've got upgraditis! I just finished a major hot-rod restoration of a vinatge Fisher 500c, and at 35 watts of push-pull tube power, it's just a bit anemic for driving my current speakers- Vandersteen 2ce's. So I'm intrigued about what experience any of you might have with either of the above monitors. Especially if either has been driven with a lower powered tube amp. The new Sierra is close to the price of a used pair of Sapphire XLs, but honestly I haven't had the chance to hear either in person.
Thanks for the help!
ACI is closing its doors and offering no more warranty or support.

There are people running Sierra 1s on tubes of that size or less.

Dave Fabrikant of Ascend is the best one to discuss the suitability of Sierra 1s and your amp with.
Thanks Newbie! I was aware of ACI's closure, but have heard so many great things about the Sapphire XLs. But I will try to get in touch with Dave at Ascend. Thank you for the info!
I do own both currently, and drive them both with solid state so I can't comment on how they sound with tubes. But I will say that I do prefer the Sapphire XLs to the Sierras.