I have tubes in all components except for my streamer. No hiss, none…not a bit, dead quiet… If you have hiss, there is something wrong. The speaker efficiency on mine is 90db.
For me each additional tube component was synergistic and brought my system to a new level of realism. Now over the last few years those tubes came from the same company, Audio Research Corp… so there was even more synergy there since they were designed and built together.