Simaudio XLR vs RCA Output Level
 

I recently acquired a Simaudio 300D V2 DAC and I have discovered that the XLR outputs from the DAC are audibly lower than those from the RCA outputs. It's not a subtle difference either. My preamp is the McIntosh C22III and if you assume that the volume control knob is a clock with the volume knob being able to go from 7:00 all the way around to 5:00, I would have to increase the volume knob to around 10:00 with XLR cables to get the same output as that by RCA cables when the volume knob is at 9:00.



I contacted a friend of mine that has a different Simaudio DAC, I can't remember which model but it's newer than mine. Anyway, his is connected to his McIntosh C2300 preamp and he is experiencing same issue. I always thought that the XLR outputs should have the same or higher output level than the RCA output from the same unit. Anyone else experience this?



My concern is that by using XLR cables, it will require more work for my preamp over the long run because I would always be using more gain.



FYI, it didn't matter what quality of cables I was using, they all had the same affect.

According to the User Guide the output is 2 volts through either output indicating the XLR jacks are for convenience only. If your preamps input sensitivity is higher for the Balanced inputs that would account for the difference on the volume control. In theory your preamp should sound better at the higher volume settings as that would be closer to unity gain.

It should sound better with XLR at higher volume? If so, should I stick with XLR? It’s surprising the volume difference between the two connections.

That's the theory with volume controls and I have found it to be generally true especially mechanical ones. You would have to look at the specs on your C22 and see if the sensitivities are different for the two types of inputs but based on what you are describing I would suspect they are. The unit itself doesn't care at what level you run the volume.

I’m considering returning the DAC and doing upgrades elsewhere.

Simaudio XLR vs RCA Output Level
 

Xlr outputs should be putting out more volts then a rca would. Sounds like they are using the xlr off of the rca outputs and the voltage is the same. So it’s not a truly balanced output
They just added them for convenience
And your McIntosh xlr inputs are made for the higher voltage and is a true balanced input and is made for the higher levels of voltage

I emailed Ron Cornelius at Mcintosh regarding the issue and the answers that were posted above are correct. He said that because the Simaudio DAC outputs the same voltage from both the balanced and the unbalanced outputs and that the C22 III has an input sensitivity of 2.5 Volts unbalanced and 5 Volts balanced, when using the balanced outputs from the DAC one would expect to experience a 3.0 db drop in volume.

It would be informative to contact Simaudio and ask them about the topology of their XLR output stage. Only then will we know if it is truly balanced, pseudo balanced, or an unbalanced output masquerading as a balanced connection. You can’t tell by the output level.

I decided to send the DAC back and will be looking for something else.