Salk bookshelf or Dynaudio bookshelf? Or something else?

What you should decide first is which room/system you want to upgrade, or where the speakers will ultimately end up. Will they be in the larger room? The smaller room? Placed close to the wall, or well into the room?

A small bookshelf like the Evoke10 will be too small for your larger room, especially without subs. The larger Special 40s could overload your smaller room, depending on your taste, but the Special 40s will certainly require room to breathe for best bass response, based on what I see in the Stereophile measurements. So if you can’t pull them away from the wall in your small room, the 40s are probably a no-go.

If you can’t audition anything locally, stick with products you can return or purchase under a trial period. Ascend Acoustics, Spatial Audio, Zu Audio, and Omega are all comsumer-direct brands that offer generous trial periods. Of these, I only have experience with Spatial and I feel they offer one of the best values out there. They may be beyond your budget but they do compete with many speakers of twice their retail cost. Since you mentioned wanting accurate sound of upright bass, you’d be hard pressed to beat an open-baffle design at any price.

Salk makes such a wide range of products, with a wide range of driver types, that I think it’d be impossible to ascribe a house sound. It appears that linear frequency response is one of their design goals, but that doesn’t mean all their speakers will sound similar. Even a 1db dip or peak at a midrange frequency can drastically influence the speaker’s voicing as heard by a listener.

I believe Salk offers a trial period, but if I’m not mistaken, it’s only for speakers finished in one of a few standard veneers, and not for every model they make.

 If I were shopping in this price class, I’d be most interested in Salk's version of the Philharmonic BMR monitors:

http://www.salksound.com/model.php?model=BMR+Monitors