I will bet you $1000 that not a single person can reliably determinate which tone is from a real tube amp vs a solid state Axe Fx 3 in a blind A/B test. Why spend 6k on a real tube amp when you can have hundreds of physically modelled amps and pedals, not to mention all the effects and "fake" things you can do like modify internal circuits and stuff... makes no sense
This is just my two cents, but if you break it down into two components - frequency response and latency - then it's easier to imagine. With the latest modelling techniques (neural nets etc) it's possible for solid state amps to get very, very close to the frequency response of pretty much any tube amplifier in my experience. Expensive modelling amps and plugins are really nice.
The second issue though is latency - when players say it "feels" different playing through a tube amp, my hypothesis is that they are noticing the latency (or lack thereof). Any kind of digital processing is going to impose some kind of delay compared with a tube amp which is a direct electrical signal. I'm aware that the delay will be on the order of milliseconds (sound travels roughly 1 foot per ms through air) and the effect could be replicated by moving the amp further away etc. It would also help to explain the change in sympathetic vibrations within the instrument. Shorter delays and high SPLs could have a non-trivial effect on the resonance of the guitar body for example.
Emotion. I have been able to tell a difference between a digitally modeled amp and a tube one but I have failed to do so for my own amp modeled by a Kemper. I suspect good players will be able to tell even that difference. Playing a tube amp is a different experience, you feel the sound as well as hear it, your instrument works with it as well altering the sound further. Also, the pedals as well as the guitar form a singular circuit (when they are unbuffered) that acts in unison. I don’t think there’s an off the shelf model of my ac15, my sunface fuzz and my LP working together. Too many combinations. Once again, music is a very emotional thing. If the knowledge of playing a good roaring tube amp makes you feel better, you’ll play better. If the knowledge of having a reliable tone stack on a usb stick works for you, awesome.
Experienced guitarists can and they have videos all over YouTube. Most common giveaway? Aggressive pick attack. Valve amps and modeling amps respond in subtly different ways. They also respond differently to volume - that's important for guitarists who set their amp near the breaking point and use the volume pot to control their tone.
Having said that, for the average bedroom/small gig player these subtle differences are too minor to bother with. Especially when a modeling amp can accurately emulate so many different valve amps. Sounds good and you can save a lot of money!
BUT - I would be remiss to say that you shouldn't own at least one valve amp. Take the one you emulate the most and buy it. You'll be happy!
