Tube Power vs Solid State Power

I’ve now owned a few SS amps and a few tube amps…. Mind you, I now own a really hi-end tube pre-amp and power amp set and I’m loving the tube sound…

I compared the $35k Gryphon to the $20k ARC and my ear goes to the ARC amp every time… 

you listen and learn… no right answer…right boys…?

It isn't true that 20 watts are 20 watts. One may be 40 volts at 0.5 amp, the other 10 volts at 2 amps. But does it matter to the sound? And does the answer to that question depend on the speaker (setting aside cone versus electrostatic design)?

Comparison on my amps.
1. 80 Watts class A SS amp by Junsgon
2. 125 Watts class A SS amp by Plinius.
3. 150 Watts class D amp by ARC
2 > 1 > 3 in loudness.
I will get a 100 Watts tube amp in a month or so, so I will see how this amp compares with #1 and #2 in loudness.

A watt is a watt except when it's not. The interaction with a power source and a resistor is pretty predictable. A speaker is not a resistor. It is a complex impedance with resistive, capacitive, and inductive values that vary with frequency and level. Worse, a dynamic speaker is also an electrical generator creating significant back EMF that the amplifier has to deal with, both in terms of dissipation and fedding back into the feedback loop of the amp. If you doubt me, hook a voltmeter up to a woofer and press it back and forth. 

How various amps and amp designs deal with all this is the magic and the art part of amp design. And why different amps do indeed sound different, from each other, and on different speakers. Isolating a big high sensitivity speaker from the amp with a transformer, as most tube and McIntosh amps do gives the designer a known constant load to optimize the design to, and is why most successful Klipsch, big Altec, and JBL systems are tube based. They isolate the amp from the back EMF and complex impedances, but there's no free lunch there, either. Mismatch loads and the frequency response suffers. 

Watts are only one parameter, and an easy one to market, like Megapixels in Photography. I remember back in the 60s when solid state first got started. The marketing drive was how many transistors a radio had. The more the better so the more it sold.

My current 40 watt mono block tube amps drive the few speakers I own better than several solid state amps I had that had more than double that power. I'm not implying that tube watts are always better than solid state butin my current set up, it has proven to be. There are so many other factors  like current, power supply, that affect the ultimate outcome.

Finally, current tube gear performane, as shipped from the manufacturer, is likely constrained by currently available production tubes. It has to be that way as  amp manufacturers needs big quantities of tubes, Although the current tubes available are decent and better than 10 years ago, numerous older tubes have further significant positive impact on the sound.