simple integral amplifier

[Dominique]

Hello,

my latest plan is to build a very simple integral amplifier,
using OPA549 (1 or possibly 2 in parallel per channel, I'm not sure yet) with a gain in the range of 2 to 5,
and an OPA2132 for the biggest part of the gain, possibly something like 10? I'm not sure what gain preamp and power amp together should have, maybe 40 or so?

As I'd like to have results soon, I thought about making it a modular design, one pcb for the amp, one for the power supply, of course I need an attenuator! I'll leave some space for an input selector that I'll add sometime soon. A headphone amp would also be nice to add sometime later in the same case.
That way, I could start very quickly and later on, while I'm still learning I could easily replace parts of the amp for comparison and to improve the design.

I imagine that amp to look basically like in the schematic. I'm not sure if I'd better put a resistor from the signal between both amps to ground.
Also, I've seen that the volume pot/attenuator usually sits right at the input. But as that changes input impedance with the volume setting, I wonder if I'd put the attenuator between the OPA2132 and OPA549?
And I've still some homework to do and read about Zobel networks to know if I'd better use this or not.

I'd be very glad for some help!
Cheers,
Dominique