Many of us have seen it, so many people these days seem to be making the switch from valve amplifiers to virtual amplifiers (profiling amplifiers such as Kemper or Axe FX) and it makes me wonder what the comparisons, positives and negatives, between each of them are in order for me (and many others) to determine whether it is an investment worth making. For this question the vitual amplifiers in question are the Kemper Profiling amplifier and the AXE FX amplifier since they're the virtual amplifiers that many seem to be going for.


What are the Positives and Negatives of each?

Can virtual amplifiers replicate valve amplifiers enough so it is unnoticeable? (is there really a difference in sound?)

  • 1
    I wonder if this is going to be closed as opinion based. I know a guy who plays a kemper and I'd never say this to his face but I hate it. Somehow digital still has not found that fabled ability to completely replicate any other sound exactly. I find the solid state analog Tech 21 products to be a much better approximation of real tubes than anything else, but nothing replaces tubes, imho. Oct 13, 2017 at 4:02
  • Tried to make the question as non opinion based as possible :). Hence the ‘pros and cons’ are non opinion biased. Interesting take, what kind of genres do you usually work with?
    – John
    Oct 14, 2017 at 2:38

5 Answers 5


The difference between valve amplification and valve emulation is in the response.

The emulation is attempting to re-create the filtering and frequency response from electrons physically moving across the anode cathode gap of a tube. This is currently mostly done with notch filtering and manipulating the digital signal. It is a similar process to the way the synthesizers create "truer to life" sounding instruments. Modern methods will get closer to the real thing, but it is unlikely that they will ever re-create that actual sound and response. They will probably get close enough that it doesn't matter to many people.

There is much variance in tubes, depending on age, manufacture, materials used etc. A digital version won't match that.

There is a new product out that is basically a "tube on a chip", recreating the response of a tube amp in a micro-chip. I haven't heard it, so it may all be marketing. The product is called Nanolog and was developed at the University of Alberta.

An advantage of digital emulation of a tube amp is stability. Tubes require regular maintenance and replacement and are fairly fragile. A solid state digital amp is much more robust.

A disadvantage is if you have technical issues with the digital amp it is much harder to repair, often the whole unit being a loss if one part fails.


I'm sure subtle differences could be discerned between valve amps, virtual amps and between the various models of each. I'd suggest that they are minimal, and largely about how the player FEELS rather than what the audience HEARS.

There's nothing quite like a cranked-up AC30 shifting air just behind you on stage. But the lack of one makes it much easier to achieve a good overall balance out front.


I practice through a Behringer V-AMP 3. It sounds cool, but I have no experience with actual amps as I mostly play drums. Modeling amps have been around for a fair while and I don't think they've achieved much success in replacing the ethos of real amps. Isn't the jury still out on solid state amps vs tubes? It's been long enough that you'd think that one would be decided now if it were going to have a definitive answer. Moreover, if one could not satisfactorily replace tubes with transistors, it seems unlikely modeling is going to be able to either.

I have a fair bit of experience watching guitarists use amps. One thing I will say is before we even get to talking about sound, almost anything virtualized presents a different interface to the musician or creator. One is interacting with a simulation driven by a computer mediated interface. There are many pros and cons in this tradeoff, but one must be very clear they are different things. Some of the pros are lots of choices and the ability to recall complete groups of settings via a preset. Some of the cons are lots of choices and there tends to be vastly more user interface surface, some hidden, some modal, etc.

Of course to be truly realistic in modeling real world amps, the simulator should fail in mysterious ways some of which can be fixed by physical manipulations of the box. The emulation might occasionally switch to a completely different model for 15 seconds or so. One might consider building six or eight fake tubes in under a panel on the back. There'd be an extra or two of these and one would have to switch them every now and then. Enterprising simulator developers would design the system to require buying new fake tubes regularly as a profit model.

  • "Of course to be truly realistic in modeling real world amps, the simulator should fail in mysterious ways some of which can be fixed by physical manipulations of the box." <--- this!
    – theGleep
    Oct 13, 2017 at 19:38

I own and use both.

The difference could be compared to actually driving a car and playing a video game. You may get the same result - travel from point A to point B - whether actual or virtual - but you did it nonetheless.

Real world applications are live and recording music.

Playing live tube amps are heavy - sometimes tempermental - and heavy. I like using tube amps live because in my opinion the experience physical and aurally is second to none. Moving air - tonality - playability - all come as part of the package with a tube amp.

I use an older elevenRack live - I use in ears for monitoring - my rack setup in small and light - FX built in - small rack, midi pedal and a few cables and I am ready to go.

If you listen thru in ears to a tube amp in another room mic-ed up there is little difference in your overall tonality as long as you have taken the time to dial the virtual machine in correctly.

Recording guitar using virtual amps or live amps can depend on your desired outcome. Most guitar sounds in rock, country, pop and most commercials recorded over the last 10 years or so have been modeled amps - no live amps - and there are rock records that have ElevenRack, line 6, Kemper and other virtual amp devices on the entire album - and major touring racks nowadays are outfitted with AxeFX and Kemper - among others.

Tube amps are LOUD - and really need to be turned up to get a good tonality from them. Virtual amps sound great out of the box most of the time.

Purchase both and see which direction you prefer to go. There are advantages and disadvantages with both depending on the situation - this is something that would be hard to choose one over the other all the time I suppose - but your mileage may vary.

Rent a rehearsal studio for a day and rent lots of tube amps and rent some amp modeler hardware as well and spend the day literally playing thru everything and making comparisons between them all - then you may be able to make an educated decision based on your new found experience.


In my opinion I don't believe the audience knows or cares most of the time if you have an amp on stage or not. As long as it sounds good to them it really doesn't matter.

As I mentioned before - a mic-ed up tube and and AxeFX going through the PA both sound awesome - and many club and touring sound guys will tell you the same thing.

  • well to be fair, this question is 5 years old! changes yo
    – Some_Guy
    Oct 21, 2017 at 3:54
  • What changes? Touring musicians are using BOTH virtual AND tube amps - and club musicians are finally getting wise to virtual amps and IEM monitoring ensuring a clean mix. Oct 29, 2017 at 16:53
  • virtual amps today are much better than 5 years ago is my point
    – Some_Guy
    Nov 21, 2017 at 10:40

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