Unfortunately looks are deceiveing… they are not even a close comaprison…
DMAN PCI:
18-bit delta-sigma A/D and D/A converters, 16-bit (or 8-bit) data path.
DAC's vary. All of the low enders from AKM and Crystal are delta sigma with on-board opamps for volatge outputs, most not very good at all.
Basically an OP amp (operational amplifier) that is used in the input stage (before A to D) is a key component for a crisp, clear, signal and it is better to have it as a separate component then integrated one as used in the DMAN.
2496:
All audio channels support 24-bit data width and any sampling rate from 8kHz to 96kHz.
Converters used
Audiophile 192 AKM AK5385A AK4358
Audiophile 2496 AK4528VF AK4528VF CS8427
Delta44 & 66 AK4524
Delta1010 A/D AK5383 D/A AK4393
The DMAN PCI looses in ALL categories…
The 2496 has a better clock, better converters, a greater data path (true 24 bit recording on hardware level), higher sample rate (up to 96K), better drivers, etc… basically, besides the similar appearance, the only thing in common is that they are both PCI cards