The volume should not change with break-in. What you may have accidentally found is there is a 20 dB attenuator for use in system matching. The “Filter” button on the remote engages/disengages the attenuator. 20 dB is a pretty significant change so I would turn the volume way down on the preamp then play with it to get a feel for how it works in your system. Some folks think the DS sounds better with it disengaged and a few think it’s better with it engaged. One other thing, you can run the DS at pretty much any volume above 50 or so into the preamp, but most folks run it at 100. The main reason for running a lower volume is to get the preamp volume control in the “sweet spot”.
I find with my DS that I need to turn up the volume more than I do with other sources going in to my integrated amp. So if I switch to the CD player I have to turn the volume down first. Filter is set to the higher volume too. Is this normal for a DS?
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.