There is also this thing, minsan im sure may chances din na mas maganda pa yung tunog ng amp sim compared sa tunay na amp.
"well this is a real amp, of course this sounds better than that blah blah".
can't argue with that because you can never sound a 100% like the real thing but for sure you can get great results with amp sims too. i've been using amp sims and real amps for years. iba iba din talaga ang results pero i wont hesitate to use an amp sim kung mas bagay sya.
but you know, if there is one thing i learned, it is that a great majority of listeners don't care if that's a real amp or not. they hear the song as a whole, not the amp cabinets or what not. amp sim or real amp, if it sounds good then it sounds good.
The quest for amp simulation in the studio has been here for decades. Even the old Motown recordings did direct to board guitar recordings but thank God there was no distortion on most of them. Cab sims and load boxes, as well as iso cabs have all been invented in order to make guitar recordings easier without having to worry about unfavorable acoustics of a room.
The dawn of digital modelling had promised to solve all these issues, but what most guitar nuts agree to is how uninspiring the dynamics of amp sims are. If you play high gain (which is highly compressed) it won't be much of an issue especially if you use EMGs. But if you play bluesy or mid-gain stuff where you want high responsiveness to pick attack, amp sims seem to fail at that. And in recording, being inspired is the key to good results.
If you want to use a real amp, the next question is "what amp should you use?" If you see a REAL Peavey Bandit in the recording studio, can you use that to get a saggy Mesa Boogie Recto sound? Maybe not. Even with the best pedals. So as a fallback, amp sims are there to get closer to the sound without having to borrow or rent a Mesa Boogie Rectifier. But given the chance, source out equipment before setting foot to the studio.
I guess this is pretty parallel to sampled drums and real drums. You want that famed 60s Black Beauty Snare drum sound. But you don't have one, so some drummers would use a drum sample of a BB. But then again it is the call of the producer if the BB snare sound is what the music calls for.