It might be your speakers. Nestorovics are quite old. Do the woofers have foam surrounds on them? If so there toast unless you have had them repaired. Try switching speakers?
Replace pre-amp
I have a Lazurus cascade tube pre-amp. I like the sound but one channel gain is lower than the other and I don't know if a fix is cost effective or not? Yes, I've tried different tubes. Any recommendations on a tube pre-amp with phono stage for $1500 or less that would be as musical as the Lazurus? Thanks. I have an SS Oddysey Stratus extreme amp, Nestorovic 5 AS speakers and a Marantz 2400 sacd/cd player.