Watts are watts?

Watts are watts except when there is some dynamic headroom built in, let’s say 3dB.
Then watts are not watts.

Watts are watts, except when it comes to my preference for tubes over solid state. I found, after many years of having both types and from different manufacturers, that tubes are what makes my music brain happy. I prefer the envelope around the midrange far more with tubed phono, pre and power amplifiers.

I drove Maggies for a while with a 150 watt NAD...it never broke a sweat. On the other hand, a 125 watt HK crapped the bed.
For the most part, when I've had Maggies, I had at least 225/channel.

Are tube watts really "stronger" than SS watts?

Of course not, the differences lie in how the two types of amps operate and, thereby, the application. Tubes are current source devices whereas SS amps are voltage source devices. What this means: IDEALLY a SS amp will maintain a fixed voltage whatever the load resistance (or other parametres). Accordingly, the IDEAL current source will provide a constant current to a load despite changes, in load resistance, etc. As you know speakers are variable loads (depending upon frequency etc.) so the inherent characteristics of each circuit will invariably affect the audible result when driving any given speaker.

As mentioned above, tubes are generally happy with high impedance speakers, full-range speaker units (due to their impedance & phase characteristics that are often countered by the tube amp’s output circuit characteristics).

Most mainstream speakers have been designed to operate with voltage circuits—however, this doesn’t mean you do not get excellent results with tubes in many cases; there are even tube circuits without output transformers that offer characteristics of both designs... (one of Atmasphere's team is an Agoner and very knowledgeable on this subject-not surprisingly!). Regards

Back in the mid-70’s, I considered both Maggie’s and DQ-10’s. Both present inefficient loads for amps. Ended up getting the DQ-10’s, based largely on sonic preference. (I might not have auditioned the Maggie’s in the best room—possibly being too close to a rear wall.) I used a Dynaco ST-150 (75WPC transistor amp) and then GAS SOA (80WPC solid state unit) for the DQ-10’s. Neither one likely had sufficient power to make the DQ-10’s sing.