No volume control when playing native DSD

My system is comprised of an RME ADI-2 DAC, Hegel H20 power amp and Spendor D7 speakers. I am presently playing my CD library from a USB drive attached to my laptop and streaming Qobuz from the same laptop. 
The problem is that, if I want to play DSD files in native format, I would not have any volume control. DoP would work, but DoP is not DSD native. I listened to some DSD albums in native format on another system and DSD sounds better than my PCM files from CD or Qobuz, as well as better than DSD over PCM conversion made by my DAC.
The question is: Do I really need an analog preamplifier in order to play DSD files in native format, or is there a workaround this whole issue?
Your help in this matter would be highly appreciated.
Is it possible you are attenuating the volume from the source (laptop) somehow? It seems to me you should be sending a line level digital output to your DAC from any file source and controlling volume with the RME, right?

You don't mention how you are connecting your source to the DAC but is it possible the different methods the laptop is transmitting your files are adjusting volume in advance of your DAC?

DoP delivers the exact same DSD bits to a DAC that the native stream does. However, if you try to change the volume of the PCM stream, you destroy the signal. So, even though DoP is bit perfect DSD, it is not an option for doing volume control.

No software does volume control on the native DSD data.   There is just not enough computer power and, even if there were, it is not clear exactly how to do it in any reasonable way.

To do volume control for DSD you need an analog volume control in your system somewhere.  Some DACs provide that function. Alternatively you can get an inexpensive volume control like the Schitt  SYS Volume Control and 2-Input Switch. It has 2 inputs and a volume control. It is basically a 2 input passive preamp. You can use it as a simple volume control or you could get a separate DSD DAC and use the switch to go between your current and the new DAC.  
If you get a proper high quality analog preamp, you will gain the needed volume control and achieve better sound by running the Dac at full volume.

I’ve tried Direct from my Dac and the preamp always wins (provided you can afford a good one with a transparent volume control).

I also happen to use an RME UFX Interface in my video/audio workstation.  They supposedly benefit from power supply upgrades.