Re: Tube amp vs modeling. Is there latency?
The latency of good modelers is in the 2-6 millisecond range. That's the equivalent delay of standing a foot or two further away from your amp.
I'm sorry, but you're not noticing that. It's in your head.
That is spot on. There is always some latency with any gear you use, you realise it or not and late modelers feel instant-ish under 10ms.
More than that, some (older) tube amps has a measurable latency or feel, depending on the circuit, making certain players nuts to record tight in time. It does not literally delay like processig zeros or ones in modelers but the attack or signal run-up where it reaches its peak can be easily more than 10ms. I can't name certain models because they vary a lot even in the same model range but I can remember of a certain modded Plexi we had around that was especially sleepy. It had great texture but it was extremely hard to play in time for a new player on it. We solved it with boosters that kicked the initial transient really hard so the amp got a much bigger kick from the start than it would get from a bare guitar signal.
For a fast response tube amp, JCM800 is a good example. It is well known of its edge. If you A/B it with a regular Plexi, you can feel the difference instantly.
Solid state amps have a more instant response in general. Very fast players with lack of tube snobism may prefer them to tube amps.
I'm not trying to generalise at all, I'd just say after having been doing it for more years than I'd like to admit, I could see a tiny little tendency (with exceptions of course). Everyone who can play well to the click plays spot-on through his own amplifier. A plexi guy tends to rush a little playing through an unfamiliar SS amp and a SS guy tends to play a little late through an unfamiliar tube amp in the first couple of minutes until the mind starts to compensate the difference.
So... If the modeling unit is well-made (does the AD/DA conversion and signal processing fast like it should) it is supposed to be not that different from playing the real stuff 3-4 foot away from the speaker.
Computer based stuff (Amplitube, BiasFX and the like) come as a completely different story as they depend on your computer and audio interface. The operation system (regardless of the actual platform) must be optimised for ultra-low latency, the audio interface must be able to operate with very little latency and the DAW must have a perfect delay compensation to place your recorded track exactly where it happened at the moment of tracking, relative to the background tracks. If any of these lack a little (for example the interface gives a false latency report or you have some resource hungry background app running on your computer) you can easily end up in the latency issue hell.