This chip assortment is definitely a mixed bag. Alongside stellar performers like the AD8610 and the AD8512 you have real dogs like the OP281. Let me tell you about the 281:
Slew rate: 25 V/ms Decent audio opamps measure this in V/us, and 25 V/us -- same signal level in 1000th the time! -- is pretty easy to hit these days.
Gain/bandwidth product: 95 kHz. Chips with a GBP of 4 MHz are considered dogs for audio use. Chips with GBP in excess of 95
MHz aren't unheard of for audio.
Noise: 70 nV/rt.Hz That means that at 20 kHz, you'll get about -80 dB of noise relative to a 1V signal, which isn't bad, really. (It gets better as the frequency goes down.) Still, common opamps used for audio are down in the single-digit nV/rt.Hz range.
I'm deliberately picking on the worst chip in the batch. There's some good stuff in here. But, I do wish they'd put something more interesting in like the AD825 instead of these jellybean parts.
Also, beware that the chips aren't all op-amps. 8 or so of them are instrumentation or differential amps.
Some random thoughts on the other chips in the kit:
OP184: on first glance, it looks a lot like the Burr-Brown OPA131, the older generation of the well-regarded OPA132. Could be usable in an amp...
AD8628: rather under-specified for audio (it's worse than the OPA131) but extremely low noise specs. Could be interesting to try in an amp, just to see.... Also the AD820, which is specified like it's an early version of the AD823.
AD8606: Similar to an OPA132, but better in most respects. Not quite as good as an AD823, but quite respectable. Also, it claims 80 mA output current. Not bad at all!
AD8007: A current-feedback amplifier with 600 MHz GBP. That's not a typo. 600 MHz! Keeping this dude stable sounds like it would be a minor nightmare... This chip was released just this month, so the datasheet on the included mini-CD doesn't have many details about the chip. There are a few other similar chips in the kit, too, such as the AD8014, a 400 MHz CFB chip. Yikes!
But you don't have to go with a CFB to get triple digit bandwidth. There's the AD8021 at 490 MHz at G=1. At G=10, it's a "mere" 150 MHz. Zoom zoom.
The microscopic chip is the AD8072, by process of elimination. The chip is so small that they could only fit three letters on it.
It's not MSOP -- they call the package uSOIC. Hmmmm...