I didn't like the Envy in Dallas. I was underwhelmed. I have not heard the Primavera or AIC-10, neither were there to try. I did try the WA33, and wasn't wowed. I tried the Envy 2 different times, hooked to a Lina DAC and Clock and then to the May KTE. Neither did anything for me. Don't remember the source with the WA33. I used my own D8K Pro with both the Envy and WA33 to give me a good baseline. I also tried the Envy with a Caldera. I love my 2A3 Aficionado, especially with a pair of 1932 Single plates. I don't feel at any point that I am giving up anything sonically with 2A3s versus 300bs in my small sample. Clarity, resolution, saturation and pacing are top notch. Plenty of power for everything I own and use and I love the way it looks. Something about a 90 yr old pair of tubes that gets me going. I will forever love this amp, whether or not I try a 300b amp down the road. I would be more apt to use a 300b as a preamp vs a headphone amp. Maybe there are other 300bs I'd like more, but I didn't find what I heard worth the money. In speaking with my tube broker he doesn't believe that 300bs are necessary for headphone amps. I don't know if it was how the Envy's were set up, but I couldn't get a single headphone past 8:30-9 on the volume pot without blasting my ears into oblivion. I tried every headphone available, but kept my D8K Pro as my baseline since I know it so well. Most headphones were on low gain and never went above 8:30 on the volume pot. That could be more an issue with voltage from the DAC and gain, but I found the 300b headamps I heard to sound good, at times great, but not consistent enough to make me buy one. The Envy and WA33 were both quiet which I liked, and the Envy is flat out gorgeous. I was surprised I didn't like either more. Preferences still rule the day...
The Primavera, Riviera, and Viva are beautiful amps and the top of the heap. They are out of my budget so I don't entertain them as possibilities in the next 1-2 yrs. I have not heard the WA23, but at that price point I think I would look for a Auris Headonia and roll in my Single Plates.