Is there a way to convert 600R T-Pad to 150R

[Ilya]

I'm going to rack my Spectra Sonics cards. In the manual they suggest using 150R transformer primary for dynamic mics and 600R for condensers.
I'd like to put a stepped T-Pad before the input transformer. The problem is, all resistor values are different for 600R and for 150R. Is there any simple solution to this?
I thought of using 4 pole 12 pos switches but they are very hard to find. I also thought of using relays but this promises to be very expensive.
Maybe it's possible to work out some circuit that switches in additional resistors in series/parallel. It looks like all the resistor values should be 4 times less for 150R, I just can't find out how to do it simply.
Or maybe I'm going in the wrong direction and I should just leave the 600R T-Pad and switch the primaries only? I don't think it would be a good solution though.

EDIT. It just came to my mind that I can put a T-Pad after the input transformer... Hmmm, would it be ok though...

 

[emrr]

You don't really want to put a T pad anywhere near a mic input.

 

[Ilya]

[quote author="emrr"]You don't really want to put a T pad anywhere near a mic input.[/quote]
Why not? Can you explain it further please?
I don't want to put an attenuator at the output because as Joe (JLM Audio) said these cards can drive 18 dBm max IIRC so it's better to put a pad at the input.

 

[NewYorkDave]

Because generally, you want to reflect a balanced impedance of 1500-2000 ohms (or thereabouts) to the mic and 150-200 ohms to the preamp input. A T-pad is unbalanced and reflects the same impedance in both directions, so it's the wrong pad for the job. Instead, use a U-pad or an O-pad, depending on the amount of attenuation you need.