Edsonic
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To clarify for the OP;
If I'm reading it right, the above discussion about the ZBIT means using that between the CPS3 and the unbalanced input on the amplifier, instead of the balanced input option on the 84UFO2. So then removing that option from your order and adding on the ZBIT. It's the same transformer and the same function either way, with the ZBIT having the flexibility of attenuating signal output of the transformer vs. the fixed (full) output of the installed transformer input on the amplifier.
One way or another, a balanced signal must be converted to unbalanced before going to internal input of the amplifier. The PSA BHK amplifier you have runs unbalanced, not in differential mode, so then does this same thing, the balanced input being converted to unbalanced prior to the amplifier input stage.
Differential mode uses a separate voltage amplifier each for the "+" and "-" leg of the signal. It is rare to see a fully differential power amplifier because it essentially doubles the cost. OTOH, one could go 'Full Monty' and get a pair of two-channel amplifiers and connect them in balanced mode, like Forum Fellow CAJames has done.
An amp or preamp having -balanced connection- at input and/or output, does not a priori indicate that the device is truly balanced (differential mode) in operation. As example, almost all pro gear gain / preamp sections or outboard devices operate single ended (unbalanced) in function; and if it's indeed "pro", everything has balanced inputs and outputs.
I'm a bit confused about actual operation of the PS Audio DirectStream DAC in this regard, due to its use of a transformer in the analog output. Is this just for the gain, or is it for conversion of SE to balanced out? They don't make it clear whether the DAC section is balanced or SE. Even the Holo May DAC description requires full reading to glean that it is indeed balanced in operation. This is what I like so much about Denafrips DACs in their description, citing "dual mono arrays DAC", leaving no doubt as to which mode of operation.
In any case the PSA phono stage is definitely single ended, with a (converted) balanced output option. In that case I might prefer using the RCA unbalanced out to save trouble of having to convert it back to unbalanced as required by the amplifier. You lose 6dB in that event vs. balanced out, but easily counteracted by setting the gain from 44dB to 50dB, e.g.
If you want to keep everything as balanced connection until the end, then the -differential mode- Decware ZTPRE would be the way to go, which would still require a ZBIT between the preamp balanced out to the amplifier unbalanced input, OR sans-ZBIT to the balanced input (to the inboard transformer) of the amplifier, if you go that route This would be equivalent to what you have now, with the truly balanced BHK preamp feeding the BHK unbalanced amplifier via balanced connection.
Were it me, I would just use the RCA unbalanced outs of both the DAC and the phono pre into the CSP3 at the outset. If at some future point I thought I might like to make full use of the balanced DAC through a balanced preamp, I would then get the ZTPRE + ZBIT.
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