I do not believe there is much advantage in using tubes with lower efficiency speakers. Tubes really shine in single ended triode configuration (300B tubes for example) into a high efficiency horn speaker at preferably 8ohms not 4ohms.
In my case I have a 300B tube amp into Klipsch Forte IV at 99db that sounds so holographic and realistic and musical.
When I tried KT88 and KT150 tubes into my Dynaudio speakers at about 86db and 6ohm it still sounded very good but not necessarily better than my Luxman Class A solid state amp or my Naim Class AB amp. So not much advantage to tube amp in that configuration IMHO.