System Upgrade

A hofer you have totally different gear. 

This gentlman has two really viable choices change the speakers or change the amp which then might necessitate other changes.

A pair of Focal  Sopras or Persona 3F are both more efficient have deeper bass and greater dynamics and the Personas would sound fantastic with the rest of his gear they are 92db efficient.

The Leben gear is excellent moving to more exciting speakers will perk up that system.  A 7db gain in efficiency is huge and his leben would be coasting not to mention the brighter sound of the Paradigms would complement his warm sounding components.

Peachtree Nova 300 will make them shine0

What tubes do you use with the  Leben CS600? Its first iterations used EL-34 or 6L6 tubes with a selector switch between eiher type.
Have you tried EL-34 tubes? Though, indeed, 32W is not a perfect match for Harbeths, with EL-34 tubes you would get a warmer and mellower sound.

Thank you All for your help. 

Re. Impedance it has always been running at 6. 

The Leben is the first iteration and I have not switched between the two options.

The Room is about 6 meters by 6 meters.

The PS Audio is the Directstream.

Listen moderately loud.

It seems like my only options are to change the amp or the speakers. I will also try the other modifs. Suggested and see what that brings.

Thanks again to All. 

I agree I have totally different gear. Nonetheless, the most obvious problem that any of us can diagnose on the internet is that his amp is underpowered for his speakers. You need a solid 80 watts for the SHL5+, 150 for larger rooms. As someone else suggested upthread, this can be easily tested without much cost or effort (order a 30 day trial or borrow an amp).

I suppose room placement is another easy and free thing to investigate, but whatever the case, the amp is underpowered. Speculating about warm voicings and such seems to me like medical diagnosis by text message.