Jwm, thank you for sharing how you're doing this! Since you're recording to PCM, I understand your preference for the Benchmark. I'm strongly considering going with double DSD for my recordings, so the DA-3000 makes sense for that based on what I'm reading.
I'm hoping to record while I'm listening and to have a recorder always connected for that purpose. So, I'm not surprised, but a bit disappointed, that you're hearing an improvement in sound quality by disconnecting the parallel cable to you amp when you're attaching the Benchmark. I see that Benchmark's analog input impedance (through it's XLR inputs) is 200k ohms. The DA-3000 is only 22k for the RCA inputs and 10k for the XLR inputs. This suggests that the Benchmark would be better isolated from the second parallel output on the Io, but it still is an audible degradation to have both connected. Too bad. :-(
Another question about the Benchmark... The specs show it as having only XLR analog inputs but you say you are connecting with RCA interconnects. Are you using an RCA-XLR adapter going into the Benchmark from the Io?
I'm hoping to record while I'm listening and to have a recorder always connected for that purpose. So, I'm not surprised, but a bit disappointed, that you're hearing an improvement in sound quality by disconnecting the parallel cable to you amp when you're attaching the Benchmark. I see that Benchmark's analog input impedance (through it's XLR inputs) is 200k ohms. The DA-3000 is only 22k for the RCA inputs and 10k for the XLR inputs. This suggests that the Benchmark would be better isolated from the second parallel output on the Io, but it still is an audible degradation to have both connected. Too bad. :-(
Another question about the Benchmark... The specs show it as having only XLR analog inputs but you say you are connecting with RCA interconnects. Are you using an RCA-XLR adapter going into the Benchmark from the Io?