Tube amps under $7500

@hickamore   I had a pair of Legacy Focus paired with a ModWright amp.  Always smooth,  natural,  transparent,  detailed,  excellent bass control.   I had previously sold all my tube gear.  As good as the ModWright was I wanted some of that tube warmth back.  I found the ModWright neutral,  but warmer than ARC tube amps when I tried that route.  I ended up being happy with a 6L6 tube Air Tight amp although I wouldn't characterize it as particularly warm or romantic.  

What I really wanted in the end was different speakers.  I still enjoy the Air Tight,  but wanted to experiment with options for my current speakers.  I was considering a ModWright hybrid integrated, which fits all your requirements except being a tube amp!  Seems like you are pretty averse to tube maintenance though.  I think I would have enjoyed the ModWright,  but ended up with another hybrid integrated that doesn't meet your aesthetic.  Only pre section tubes, but very smooth, pure, natural sound as I expect from a good tube amp.  Maybe a good hybrid could get you best of both worlds. 

If you want romantic sound and mention taking advantage of speaker efficiency,  why not something lowerer powered?  Maybe not single digit,  but 20-30 watt range. Something like Allnic used could fit the bill and check all your boxes if you're willing to wait for silver to be available. 

@porchlight1 @yoder  Thanks to this thread I am now an uncommonly well-informed tube amp shopper. Much appreciated.

@hickamore 

just had a thought:  what about bi-amping?  You could use SS on bass, and would give you more tube choices for treble.

@mdalton Interesting thought that had never occurred to me. I suppose it is a given that no tube amp in my price range can match its SS equivalent on bass? And if bi-amping with one SS device and another very different tube kit, wouldn't I then get into level controls and active crossovers? Remember, I am a lazy listener, not a gadget enthusiast.

definitely not expert in this area, but four different thoughts:  (1) some tube amps come with gain adjusters.  (2) if two amps have same gain, no issue.  (3) if different gain, you can lower gain on higher gain amp thru use of resistor on interconnect. (4) use an external passive preamp (attenuator) for the higher gain amp (For example, Lab12 sells one for $750.)  Again, just brainstorming with you, am sure others know much more about this, but if it works, you could save a bunch by getting a relatively cheap class d amp for lower end, and then you can splurge on a relatively low power tube amp for tonality at the high end.