If you parallel DACs by summing their current then you'll get some SNR improvement of the DAC spec, if you steal away some of that current then the SNR improvement won't get lost. However if you use a resistor to shunt the current to 0V before your I/V stage that resistor may well increase your I/V's noise gain, worsening your SNR. This will depend on the Zout of your DAC though.
i'm using differential output so the resistor would be placed between iout- and iout+.I have a difficult problem to solve , how to make an i/v converter without feedback to have a gain...I'm investigating Gilbert cells like topology for now. I thought that maybe modulating the Iref of PCM179x somehow, i'd be having a gain opton straight out of the dac output.
On the other hand i'm the "Dolby fan" guy...so 80db SNR is absolutely fine for me. I can make use of 12 db out of the 96 db of the 16bit standard and still be better than dolby C.