Thanks for the info. I've looked at the D-76. It looks really complicated and expensive to maintain. I can't imagine the trouble involved in biasing all those tubes.
What exactly will prevent me from obtaining the best performance from the sp6/Reference 75 combo?
I understand unbalanced vs balanced. I regularly make my own single ended to balanced cables, both male and female. I also have a transformer for one line.
The remaining parts of my system are balanced. All I would need is to make conversion cables for one SP-6 input (line level, the phono is already unbalanced) and the SP6 output. After that, I'm all balanced.
I don't consider the unbal/bal issue a problem. Juat recently I had a Paragon System E tube preamplifier (ca 1977, so contemporary with the SP6) as my preamp. I connected as I described above. It worked well. Dead quiet at normal listening level. No ground loops.
What am I missing?