Software volume control issues (image drift)

I’ve been bypassing the pre-amp section of my integrated amp (Peachtree Nova 500) and using either software volume control or (more typically) my DAC/streamer’s (Matrix Element X) volume control. Yesterday evening, while listening to a very familiar album (Revolver) I noticed that the stereo image seemed to be drifting (the lead vocals for example might shift from right to center or vice versa). It’s as if the software (or the DAC’s) volume control isn’t maintaining a steady grip on the right v. left channel gain. After re-engaging the Peachtree’s pre-amp section, sure enough, the stereo image stabilizes.

Anybody else experience this problem? Possible remedies? From a user interface perspective, I prefer the Matrix volume control (because it displays on the device’s front-panel in .5 dB increments).

OK … after switching over to fixed volume in Roon, the image seems to be stable even with the Peachtree Nova’s pre-amp bypassed (and using the Element X for volume control).

If you are not using the DAC section, did you think about getting the Peachtree amp500 instead.

The amp500 was not on my radar when I bought the nova500.
Now that I have a streamer that happens to have its own DAC and pre-amp, if I could trade down to the amp500, yes, I might consider that (or another power amp). But having already bought it, I’m not confident any SQ improvement would be enough to justify the hassle of a trade.