Hi,
Regarding the slew rate, although a super fast slew rate is not really needed for audio (a lot of good audio circuits were bandwidth-limited and slow), it is essential for high negative feedback circuits such as op-amps (hence my choice of video op-amps).
This is because the output has to be perfectly aligned in phase with the input for the negative feedback to function properly.
neve discrete circuits, for instance, have a lot of small capacitors in the signal path that slow down the circuit. This is probably to eliminate stray R.F. from the audio path and make the amps more stable. (they have built-in high frequency filters)
for an amp to have a high slew rate it has to be very stable as a circuit, to avoid stray oscillations or ringing. This makes it so that a slower circuit may actually function better for audio. The important thing is that it not be too slow, or too fast, depending on the circuit.
So for op-amps you need speed, for discrete it depends.
The 1178 uses op-amps for everything, and has no relationship to the 1176 circuit other than theory of operation.
You might like the grunge it adds, JJ.
The older op-amps were particularly grungy and add a certain roughness to the sound.
But then, you have to consider the integrity of the performance.
The thing with op-amps is that once you pass through an I.C. channel strip you've lost enough information that you will notice little further degredation regarding the integrity of the track. This is maybe why processing became so important in the 80's: the sound needs to be processed to gain back some of it's interesting qualities lost in the signal path.
What you want to do to check this out is to take a clean signal (from a discrete pre) and pass it through your I.C. device. Listen to what happens to the 'livelyness' of the sound compared to it's discrete equivalent.
Or since you are a guitar player JJ.. get out a good tube d.i. play your guitar through different studio compressors and boxes etc.
I'm sure you'll find that the best boxes are also the ones that feel better to play through. There is a reason for this.
Fundamentally, there are characteristics to a sound that make it stand-out and be supportive in a mix.
The fundamental one is the performance, which is largely dependent on rhythm and transients. Then there is the 'hardness', size, and natural-ness of the sound. if the bass was rich and full it should remain so, if the highs were captivating and urgent-sounding, they should remain so.
Once you remove the feedback from the typical IC used in mixers it becomes a grungy, bandwidth-limited noisy distorted super-high-gain amplifier. Each op-amp probably has over 15 or 20 transistors inside. Not good for audio.