Merlin with Pass XA 30.8?

You may want to consider the new Coda  series 8 amplifier which comes in at the same price of the Pass Labs and has been just compared to the $14k Pass Labs monoblocks.

The Merlins like power and having a 150 on tap with the Coda would be advantages over the lower powered Pass.

Dave and Troy
Audio Doctor NJ Coda dealers

I'm using Pass XA-160.8s with modified VSMs.  I previously drove the VSMs with a modified BAT VK-75SE.  Both amps (and the XA-30.8s) have ample power for Merlins.  The Pass amps are eerily quiet and smooth on top.  Relative to the tube amp, you may initially perceive this as a loss of HF extension and air.  But I think the Pass sound is more faithful to source.  Try them with and without the Merlin Zobel-- you may not need it.  

The more I listen, I think I will keep my MC275.