Amps for Focal Maestros

I'm currently looking for new monos for my Maestros.  I currently use PrimaLuna Dialogue HP amps in mono config.  Generally, they sound wonderful but lack in the bass, especially the mid and upper bass.  I rolled KT150s and that did make a noticeable improvement, but still not where I'd like.

Part of the issue is I love the sound of tubes in the midrange and high frequencies.  My Maestros cannot be bi-amped.

I've listened to Naim and McIntosh as the only dealer in the area with a set of Maestros reps those brands.  Did not like either.

I've thought about Pass Labs XA200.8 or X600.8 and Kent at Pass Labs assures me the bass would be there.  But, the Maestros have a serious dip in impedance in the base well below 2 ohms with accompanying difficult phase angle.  I read a review in Stereophile about the XA200s driving Wilson Alexias.  The Wilsons have a similar impedance dip to the Maestros and the comment was made that they lacked bass energy.  Ugh.

Of course, it is near impossible to audition without a large outlay of cash and associated cost of return.  

Appreciate any feedback.