OP-amp bias resistance???

[oskar]

So, from what I've learnt, booth OP-amp inputs should see the same resistance to a DC source.
I'm using the rebote 2.5 here as an example:
http://www.tonepad.com/getFile.asp?id=98
First op-stage/IC2b:
The inverting input has a 510k to the output and the noninverting input 240k to Vb.
Q. Shouldn't the 240k also be 510k?
Q. Do you count Vb as a DC source in this case or should you also count the 12k resistors (12k//12k =6k) to 9v and ground?

With the same reasoning I compute 12k instead of the provided 1k on IC2a noninverting input.

Q. All this is for cancelling out a DC potential to build up on the output right? So then...
Q. If you have a coupling cap as the 1uF on the Rebote output, then you don't really need it... (As it only provide
the most minute increase in headroom)

This has given me a headache for some time and I've thought of asking about it but as you see I don't know
what the proper questions would be...

ps. The PT-80 as a comparison: Input OP:(-) 10k; (+) 1M ... Output OP: (-) 5k(10k//10k) ;(+) 1k

Does any of this make sense to you?     
I don't suggest these constructions are wrong but that my reasoning is and please someone correct me...   

[R.G.]

So, from what I've learnt, booth OP-amp inputs should see the same resistance to a DC source.

What you've learned is incomplete. More correctly:

While opamps will work correctly for AC signals if their inputs do not see equal resistances to a DC bias source, both opamp inputs should see the same resistance to a DC source for the best possible DC accuracy in terms of output offset voltage.