yes and no.  the ratings on the amps are only a starting point.  most pass products actually deliver greater power than rated.  the arc got a terrific review in the magazine as well.  89 db is above average sensitivity.  if they are nominally rated at 4 ohms and do not dip too much below 3 ohms, then either of those amps should do.  the common logic would say that the solid state amp will control the bass better and the tube amp would be more dimensional.  i have 90 db efficient speakers and am getting very good sound from a pair of custom made 300b amps rated at 8-9 watts each.  admittedly, they don't quite get the job done on large scale works, but they are only temp. until my new amp is built.  that amp will be 25-30 watts, but will have a capacity to move a lot of current.

if you are looking to spend that kind of dough, then you find the shop owner and demand the demo that you need to make an informed decision.

good luck, let us know how it goes.

tom

driving 88dB/1w/1m New Large Advents and never felt I needed more power.  If you don't listen at rock concert levels or have a very large room, a 30 wpc amplifier should be fine for those PSBs as long as it can handle a 4 Ohm load.  That Pass Labs doubles power into 4 Ohms, should be pretty robust.

Is only nominally important.  Efficiency, related but not the same is also important.  Look for speakers with a nominal 6 or 8 ohm curve.  I'm only 10 years or so into this hobby, but I've found efficiency to be more important than sensitivity, especially with tube amplifiers.  Also, speakers with big complicated crossovers give many amps, even SS amps real trouble.  What I have noticed, coming into the hobby after the "rediscovery" of tubes and lower power SS circuits, is that speaker manufacturers are doing a better job of matching driver curves within a system, using crossovers just to protect tweeters and manage rolloff.  Which is a very good thing, and my guess at why so many speakers now sound very good.

Sensitivity may matter more with cable selection.  Not 100% sure the engineering behind why, but some slightly higher resistance cable systems that are otherwise wonderful can sound dead and lifeless with less sensitve speakers, regardless of amps.  I'm sure that, to paraphrase Julian Vereker, the proper application of common sense and ohms law will explain it.

Beyond that, integrated amps being the new black, high end ones have kind of stolen Arcam/Cambridge/NAD's thunder.  You can now spend thousands of dollars on an integrated, don't buy from someone who isn't accomodating toward giving you a listen.  And don't call them back.  Or send them a Christmas card.