There are two potential issues that may explain the observations here.
First, the output level of the DS Junior is only 1.4V unbalanced, which is below the usual 2.0V standard for CD players. (In fact, many CD players and DACs tend to output a bit more than 2.0V). The specifications listed by PS Audio online are incorrect and mistakenly report 2.8V (high setting) and 1.41V (low setting). In fact, the high setting only outputs 1.4V. This was confirmed by Ted Smith in response to a previous post I made on the PS forum. However, the online spec sheet has not yet been updated to reflect the correct values. I don’t know whether this also applies to the DS Senior.
As a separate issue, I have also found that occasionally, the internal volume control of my DS Jr resets itself to 60 instead of 100 where I have left it. Thus far, I have almost exclusively used the DSJ with Roon over the Bridge II input, so I’'m not sure if the is particular to the B-II, Roon, or all inputs of the DSJ. I have a suspicion (unconfirmed experimentally) that this may have something to do with the DSJ occasionally losing it’s connection to the network, and when it is rediscovered, the volume may be set to 60 by default.