Is Nelson's pre as good as his amp ?

>The Aleph amps prefer a balanced input signal

What? These are the original single-ended solid state designs. As I recall, the Aleph 3 doesn't even accept a balanced input.

Drubin you are correct about the Aleph 3, it only has RCA inputs, but all the others are fully balanced designs and for maximum performance they require a balance input signal. If you doubt me, contact Pass and see what they say.

The Aleph 2 manual says that there is no penalty in audio quality for using the RCA inputs.

The Aleph 2 Owner's Manual says: "For the lowest possible operating noise in any environment, the amplifier is equipped with balancd inputs featuring a common mode noise rejection of greater than 60db". I basically can't find the place in manual mentioning about no penalty of using unbalanced (RCA) against balanced. However, I did see "There is no penalty for not using this plug with unbalanced oeration". "No penalty" here I think is something about using or not using the plug for RCA to switch in between 26 dB and 20 dB gains.

balanced is better if the full design is balanced. CMRR is always greatly improved with a balanced design which is always good. That is all you need to remember.