Hi devilboy,
As you
I suspect if could be a case of poor quality tubes in your particular Raven amplifier. On the other hand it’s certainly possible the amplifier just is not a good match with your Nola speakers (it happens). The Hegel seems to be a very good fit for your speakers. I would not be surprised if the Line Magnetic 805ia (48 watts of pure class A SET) (or their 845 tubed amps) paired very well with your NOLAs. I can understand your happiness with the Hegel.
Terrific sound with your speakers.
You can leave it on 24/7
No tube expense/replacement concerns.
I do get the feeling you’d hear an exceptionally natural and involving sound with the LM 805ia driving the NOLA. I know you are in a good place sonically with your current system set up, congratulations.
Charles