I have not heard the Hegel to compare, but I do drive the Heritage Specials with a Pass XA25. I also own the same LTA pre (with rolled tubes). I have no issue driving the Dynaudios to listening levels that are satisfying to me, though I am not into listening at high volume levels.
I feel that the combination of the Pass and the LTA works extremely well. The LTA is not at all a classic sounding tube preamp, but is very dynamic and natural sounding, but not lush (like an older CJ for instance). The Pass is a little on the warm side and it pairs well with the LTA.
Also, the HS speakers are a nominal 4 ohm load, so you are getting the additional power that the Pass can put into lower impedances. And as it has been measured when reviewed, the 25 watts even into 8 ohms is very much underrated to what the amp can actually do.
In my room, the setup has responded very well to every upgrade I have made, adding resolution, precise imaging, microdynamics, and open soundstage, along the way. Timbre has always been good, but got even better when I upgraded the LTA tubes this year.
Tons of choices as others have indicated, but I’ve been very happy with this combination.