Power amp recommendation for Harbeth 30.2s


It’s not that I don’t like my current setup, it’s just that I wonder whether a more powerful amp would give the music more heft.  I’m running a pair of Harbeth 30.2s through a Prima Luna EVO 300 preamp driven by a vintage YBA Passion SS 400 power amp (purchased second hand from a reputable dealer).  I listen primarily to music streamed  from my FLAC stored collection on my NAS or from Qobuz through a Bluesound Node 2 into a Chord Qutest.   The YBA is very transparent and I love the sound of my system, but sometimes wonder on certain types of music whether a more powerful amp would be an improvement.  I like the idea of a SS or hybrid power amp paired with a tube preamp.  I chose the although  the Prima Luna preamp after listening to a Prima Luna integrated against a Hegel H590 (I had previously owned the Hegel H190) and purchased the YBA at the same time.  My listening choices are varied (folk, jazz, alternative, vocal, rock (not metal), so I’m not looking for ear shattering volume.  I don’t like the idea of a tube power amp due to both cost and how hot they can run.  I’m captivated by the Pass amps, but they are expensive.  I’ve also wondered about the Van Alstine hybrid amps.  I’m throwing this out to the experts because I may be overthinking this and should just be satisfied with the YBA until it finally fizzles (it’s pretty old).  Thoughts?
bfleetwood
I was not able to find specs on your amp but YBA appears to make good stuff- but there are differences among power amplifiers that make one better than the other at a given power rating.
Also it would be good to know your budget.  
My understanding is that the build quality of the YBA amp is superb.  I don’t have the manual and have not been able to locate one, but it appears it’s spec’d at 120 wpc into 8 ohms, although I have been told that’s very conservative.  It apparently sold at $6500 new (I paid $1250).  It’s not a question of not enough bass, I find the Harbeth’s to be extremely well-balanced and I have never experienced listener fatigue.  It’s just that I wonder sometimes whether more power would be better.   Budget-wise, I’d like to spend less than $5000 (as much less as possible).  I have always been intrigued by reviews and discussions within this forum where Harbeth’s are being driven by 30 wpc Pass Class A amps.  The whole wpc thing is still a mystery to me.  What power amps have Harbeth 30.2 owners found to work best?
I demo'ed the 30.2 with a Luxman L590axii class A and thought the system sounded overly subdued, recessed and rolled off.  

My current system is a Rogue Audio RP-7 tube preamp with a Parasound a21+ amplifier and Harbeth SHL5+. 

Very smooth but highly detailed and dynamic.  The a21+ is a winner.  
In your first post you mention "an improvement" and in the last "better", but you don't specify on what axis or axes that amelioration might be achieved.  You also state there's more than sufficient bass.  If you were using 50W on them I'd say yes, go ahead and try 150W.  As it stands you're intrigued by different sounding amps, and there's a variety of amps that will give different presentations. BTW, if you check out the Harbeth User Group (HUG) you'll find a remarkable range of amps being used with different Harbeth models.  There's no orthodoxy on this one.  I think you need to audition (in store or at home) to make significant headway with this issue.