What about the modeling sound in particular fails indistinguishable? My ears aren't trained enough.

This was mentioned is a sibling comment, but I’ll 2nd that it matters more on a bluesy/rock style tone. It’s right when the power amp is starting to get saturated.

On a modeling amp, I have not heard one that doesn’t introduce extra digital artifacts into the tone. It’s like the difference between GCI and IRL.

Another is on the other end of the amplitude spectrum, very quiet playing, where I hear extra digital artifacts introduced.

As the other poster mentioned though, these differences may not come across at all in a metal/pop setting.

Everyone thinks they can tell the difference until they do a blind test.

That is true- this is a good callout. You’re brain does a lot to convince you of the difference when you know the source of what you’re hearing.

But there are always exceptions. As someone that worked as a recording engineer for 7 years, and spent time intentionally training my ears with blind tests, I can tell you that there is a definite aural difference between a real tube guitar amp and a modeling amp. Other recording engineers I assisted could hear it too.

In my limited experience(and I haven't tried the expensive stuff like Kemper or Neural dsp), the difference is most apparent to the player in the way amp and effects react to playing dynamics. For a blues player sat 'on the edge of overdrive' the effect of injecting emotion into ones playing comes through the amp in a way I couldn't get with a digital amp. This the affects the players response. I feel like a million dollars through my Fender Twin. I close my eyes and channel my Stevie Ray. It didn't happen to me through a Boss Katana. If you were paying to listen to me (as if), you would get better vfm from the tube amp.

If I played metal, or was backing a pop group, one pedal di'd to the desk sounds like the dream

I ditched my amps for Neural DSP VST' and I play somewhat similar stuff. I recommend trying them out, especially "Tone King Imperial MKII" (there's a free trial available).

That is really interesting. Can I ask a couple of things? What do you do for monitoring? What about amp induced sustain, do you lose that?

>What do you do for monitoring?

I don't play live so for me it isn't an issue, I just have set of monitor speakers to play on.

>amp induced sustain

As in Feedback? This too is applicable primarily for live setting, but I don't know how well it'd work as I haven't tried it.

I run a mid range POD HD500X, it's really really nice to not have to play around with it a ton (presets are great) and you can still get pretty close to what you're looking for without ever having to buy more gear (at least amps/pedals, guitar still matters a ton).

I think my favorite thing about it is that it just allows me to play more. I run my computer output through the rig, so everything comes out my headphones. This means I can play rock as "loud" as I want, with any song on the planet, and the whole house can be sleeping. Very much worth the trade offs for someone who just wants to play and not geek out about gear.