Hah, I knew it was a lower volume issue! Its exactly the same for me. It's like that fabulous tweeter and midrange frequencies eat up all the available power and the bottom octave falls out, which never happend with my Contour 1.1's and the R8. Probably it's because the 1.1's arent as good at lower levels, everything is diminished in scale including the mids/highs, and they also have a much smaller bass port which helps retain some of the punch. Since the 1.1's are moving to a home office setup, I have a Linn Classik coming that I picked up here on Audiogon. Ironically, the Classik and 1.1 combo is the first higher end system I had ever heard and got me interested in Dynaudio years ago, so it feels like I'm coming full circle in a way. I never forgot that punchy rythmic sound, its quite a pairing.
Anyway I'll temporarily use that as a preamp with my old SimAudio W3 and see how that works w the HS. I just can't see myself moving fully away from the R8, there is something magical about tubes and that amp in particular. And I'm probably being overly critical of the bass from the HS, its still there, just not as full as I'd like. If I like it with the W3 I can always find a used Linn pre and then have the R8 side by side with the Sim/Linn stack. Or sell the Sim and go with a beefy integrated since I tend to prefer fewer boxes. Lots of options.
As you can tell I'm not into overly analytical systems and prefer smoother, warmer tones along with weighty, punchy bass, but it doesnt need to go particularly low. I'm in a townhouse so subs and big towers are out due to neighbor concerns. The R8 has plenty of punch, but to get there I need volume, and then the highs and mids will be too loud and I'll get complaints. So I kinda know exactly what you mean.