How to get

Preamps offering tone controls or loudness contours address the no guts at low level phenomenon.

You may want to consider powered NHT M00s and their PVC passive volume control. I'm listening to a pair playing back digital files from a MusicVault Server ouput thru a HDT MusicStreamer+ DAC. You have the server; the Music Streamer+ DAC and M00s would cost you under well $500 used. Compact, neutral, detailed, punchy and if you want to take them to the next level you can add the NHT powered S00 sub. Otherwise the loudness contour suggested by Rockvirgo is a good idea.

After thinking about this for a little bit, and if cost is a major issue, you might consider klipsch speakers. From what I have heard and know about their construction, they are one of the most efficient speaker currently made and would definitely drive well at low volumes. Some people don't like them due to inherent sonic qualities from their design, but as far as efficiency at low volumes on a cost versus benefit basis, they would do well. Monitors would be more effective at low volumes, but the Dynaudio monitors are horrifically expensive due to their studio design and build quality. Anyway, I just thought I would mention Klipsch as an option since a really nice pair can be purchased for little $$ and the current setup should drive them admirably at low levels. If you add a small powered sub with the klipschs that should help balance some of the highs that will be a little pronounced from the klipsch design.

Thanks again for your responses. You've all provided some good ideas for me to think about and implement. I like the tonal qualities of the Linn speakers, so perhaps the first thing I'll try is adding a small powered sub.