2-quadrant MDAC attenuator low output voltage AC operation

[SArepairman]

So if I want to attenuate a small signal using a 2 quadrant MDAC with an offset voltage. However, when I am really attenuating the crap out of it, that offset voltage is going to get attenuated too.

So I can put a DC bias (~7V) on the input AC signal (milivolts)  to have an output of 100uV DC offset (16 bit attenuation). @ full scale attenuation with a _TINY ac signal that will be AC coupled to whatever (as I must get rid of the amplifier offset anyway). (the attenuated signal will probably be beneath the noise floor of the MDAC but this is ok! so long it is there) (tiny increments!)

 Are there any problems that I should be aware of for this? Should I use a bipolar configured AC coupled MDAC for any reason? Do MDACs for any reason not like working with signals that are very near ground?

the bandwidth looks fine.

the dac is being used as a set and forget kind of deal. I am not going to be "modulating" anything.

the op amp connected to it would have dual supplies though. I am just trying to be cheap with the DAC (dual supply MDACS have a larger package and are pricier, i'd rather avoid the external resistors etc required to turn a 2 quad into a 4 quad)

*ultra sonic frequency AC sig attenuation is of concern here
and I don't really have a set model # for the DAC in mind. None of the data sheets I read seem to describe any concerns like this on AC attenuation.

[SArepairman]

bump. I don't really have a way to test this thing without building the entire, rather pricy, circuit, and I would hate to run into a problem here and have to dead bug some 16 bit SMD MDAC

unless some kind soul wants to give me some money for a nice lock in amp 

(though at this point I don't care ill have a BGA "spider monster" assembled by the local warhammer club if it would help a damn)

does anyone have any feedback?