OBVIOUSLY 2khz is the analog section. That anyone would think differently is kind of amusing. Still, frequency response specifications without db tolerances have no meaning. The exact same component, with the exact same test material can ACCURATELY be said to have frequency response 100-2kz, 50-15khz, 20-20khz, 5-50khz, etc...if the tolerances given are +-.01db, +-.1db, +-.3db, +-1db, +-1db, and +-3db.
DB tolerances mean everything, and a frequency response "specification" without them means nothing. Still, it's all about WHAT YOU HEAR, especially when one gets into the realm of perceptual coding. It's not about WHAT IS THERE, but what we HEAR...often two entirely different things. Think of tv or movies. When we look at the screen, we see moving images. It's completely fluid, and natural looking. And it isn't what's there at all! Nothing on the screen is actually "moving". It's just a very rapidly evolving "slide show". But it's too fast for us to see individual "pictures".
That's not EXACTLY what happens with perceptual coding, of course. Actual sound IS being produced, and the waveforms are far more similar to the original sound than is the "motion" from tv or movies. But moment to moment we ARE being tricked into believing we hear complex overtone structures, and natural harmonics, which have been altered by necessity. There's no room for "purists' in this brave new world. Lossy compression, and perceptual coding are everywhere. That we seldom even think about it proves how well it works...how thoroughly our senses are "fooled" into thinking we see, or hear, something different than what is actually being presented.
If it sounds "good", then it IS good. And if it actually sounds LIKE THE UNCOMPRESSED/UNALTERED ORIGINAL, then it's GREAT, whatever measurements tell us. (Likewise, if it doesn't pass the "stink test" with double-blind methodology, then it IS AWFUL, regardless of what measurements tell us.) Measurements have their place. And they can even be useful for helping us learn WHY we hear what we hear. But they're completely useless in telling us WHAT WE HEAR!
