The 9038 Pro chips can be ran in a high current mode. This allows higher output voltage/current from the DAC chip itself. The downside is heat (which requires heatsinks on the DAC chips themselves) as well as an I/V stage that is capable of the higher voltage swings. I know of only two manufacturers that support the "high current" mode (LKS and Audio-GD). If you see the 9038/9028 in equipment without heatsinks or using normal op amps for I/V, then they are running them in standard mode, which isn't really any different from the previous 9018 generation DAC chips.