Cube Audio Nenuphar Single Driver Speaker (10 inch) TQWT Enclosure

@charles1dad 

Thanks for the quick and informed response, very much appreciated.

Yes it is a SET amp and as you pointed out slightly unusual with the -6dB, very small, and natural negative feedback, just for better bass.

@charles1dad 

Do you think an even lower watt amp would/might be even better? and do you have any suggestions?

@yorkshireman,
I can not say with any authority that a lower power amplifier would unequivocally be better, certainly as good. @david_ten is enjoying truly splendid results with his superb 2A3 SET . I feel more strongly that the absolute quality of the amplifier is priority number 1.

 The best quality SET you feel that you can afford. SET circuits are straightforward and no mystery. Key criteria are high quality parts, output transformers and very stout power supply. The Nenuphar will readily exploit these amplifier attributes.
Charles 

As far as specific recommendations go there are no shortage of worthy candidates. Have you determined a budget comfort range?
300b SET are more plentiful and are also generally more expensive than 2A3 SET amplifiers. Again, depends on what level/tier of quality you seek. The better the amplifier,  the better the Nenuphar will sound. 

Charles

Thanks again...