Sound level variations Qobuz - up to about 15/20 dB, need to adjust preamp volume by track

Try Tidal but I don’t think it has anything to do with streaming services. If you’re listening to Beethoven Violin Sonatas and switch to Metallica after you will have to adjust the volume. 
Some streamers and streaming software offer volume leveling if you are bothered by this too much. Although using this option will most likely affect sound quality in a negative way. I haven’t tried it. I use volume control to address this inconvenience. 

You need ReplayGain, which is a metadata-based loudness adjustment system that does not affect bit processing or sound quality. I know BluOS, WiiM, and Audirvana offer this feature, but it is not commonly available across platforms. Roon has a similar function called DSP volume leveling.

Certain record labels are known for having high or low gain recordings, and some do vary a great deal. If your music server has the ReplayGain software feature mentioned, give it a try. Eversolo servers have that feature. 

Hi , I remember your recent posts regarding streamers. It appears that you have something new. So did this volume issue start with your new gear ? FWIT , my modest rig is an Innuos streamer to a Schiit DAC. I stream both Tidal and Qbuzz and internet radio with the Innuos. I have the unit set to default max volume and the auto adjust turned off as mentioned above. My overall sound level and SQ is very consistent with Tidal and Qbuz. However streaming Radio Paradise and Dot1 FM , are consistent but at 2-3 db higher than Tidal and Qbuz. The radio is also a different formatting and I like it better ( I’m the exception). I emailed Innuos about the greater volume and they don’t incorporate software for that. So the only volume adjustment I do is when I go in and out of the radio stream. Since I have a Schiit Yiggy it clicks when the bit rate changes but that doesn’t bother me. Maybe contact your streamer support and ask them. Regards, Mike B. 

Different labels have vastly different recording levels.  Reference Recordings uses lower levels to properly capture the very wide dynamic ranges of their classical music catalog.  Most popular music is crushed loud with no dynamic swings so it  screams at you.  When I hear that I instantly switch to a new record.  Playlists of different  selections are therefore very inconsistent volume wise.  If it's on the same record, which does happen, it's a mastering error.  Your better equipment now allows you to hear all that better than before.  You do need equipment with a remote control to adjust as required.