Did you try both gain levels on the preamp with all three gain levels on the amp to try and find the best match? Other than that with a speaker of average or higher sensitivity it is not uncommon to hear some small level of tube hiss if your put your ear right up to the tweeter.
My 1st Tube Equipment Experience
I just purchased a used Herron Audio VTSP-3A(r02) tube preamp, as a replacement for a NAD M12. I paired the M12 with a NAD M22 v2. My first impressions are the M12 has more detail, the VTSP is much warmer, which is what I wanted. The VTSP sound is definitely different. And while it lacks the M12 detail, I do like it.
With the M12, my speakers were dead silent when music was not playing. With the VTSP, I hear a slight hiss when I put my ear very near a speaker. With the M12, I used XLR from the M12 to the M22; XLR from my Parasound JC3 jr; and RCA from my Liberty DAC. With the VTSP, everything now is RCA.
Is a little hiss common when using a tube preamp and SS power amp with RCA cables?
With the M12, my speakers were dead silent when music was not playing. With the VTSP, I hear a slight hiss when I put my ear very near a speaker. With the M12, I used XLR from the M12 to the M22; XLR from my Parasound JC3 jr; and RCA from my Liberty DAC. With the VTSP, everything now is RCA.
Is a little hiss common when using a tube preamp and SS power amp with RCA cables?