Dynaudio C1 compared to Harbeth Super HL5 plus?

Are Harbeths deficient in bass and high frequency extension?

Nope. 

I've owned them both

the harbeths are much easier to drive than the dynaudios. The harbeths are smoother and have almost no listener fatigue at any volume

the dynaudios need a ton of current and are voiced to play loud t sound their both, yet the dynaudio is a fabulous speaker in its own right

i prefer the harbeth

i now own harbeth 40.1s
they kill anything I have ever owned including Avalon eidolons

Both great speakers. I haven't heard the C1 in quite some time. I enjoyed them but recall they sounded best when played a bit louder than I like. I'm about to order the SHL5 Plus in Tiger Ebony as a Thanksgiving present to myself. With the right amplification, Harbeth's can be played at very low volume levels and you don't lose anything.

I had the C1. Then went to Harbeth Compact 7. Now I have the 30.1. I heard the SHL5+ at a dealer. As has been written, the Dyns need plenty of clean power, and sound best at louder volumes. The Harbeths are much more musical to my ears.
donjr,
Give us a review of your SHL5+ system when you have a chance. Look forward to reading your thoughts.