Panu21, I agree with Mrjstark's observation. Thirty watts should drive that speaker with plenty of power. You may have an issue elsewhere.
I believe that speaker would mate well with an SET tube amp or push pull tube amp if you want more drive. IMHO you will be giving up a large measure of harmonic information and transparency by going to a ss or class D amp.
I believe that speaker would mate well with an SET tube amp or push pull tube amp if you want more drive. IMHO you will be giving up a large measure of harmonic information and transparency by going to a ss or class D amp.