Prozor D.A.C Output

[Lucid]

Input sensitivity and impedance

CD, Tape Monitor, VCR
200 mV/22 kohms

I've filtered down to just the essential info. What this is telling us is that if the amp receives a 200 mV signal, and you turn up the volume to 10 (not 11, like Spinal Tap ), then the amp will deliver its rated power output in whichever way they've specified it.

A signal that's larger than 200mV can be accepted, but it won't make the amp any louder.

 

[Martyn Bell]

A Google search gives this result.
Increased volume with an RCA connection is generally represented by an increase in the voltage of the audio signal transmitted through the cable. The higher the voltage, the louder the sound will be at the receiving device.

 

[Lucid]

If voltage makes no difference, how do I make a comparison of RCA output between devices?

I don't believe that's what's important here. If one device has a 2V output and the other a 3V output, then so long as the amp doesn't clip with a 3V (peak) source signal then it's all good. You're only going to be able to find this out though with trial error.

What I think this all comes back to is what I wrote in post #10

If all that is clear, then what's left is that the Prozor is just a poor product.

If the optical cable isn't restricting the signal in some way e.g. you removed the little protective end caps, and the lead isn't fractured, and the output level of the signal for optical isn't turned down (separate menu for the Optical signal level on my TV, check yours), and there isn't something like a source-signal-level-per-input adjustment turned down, then it's down to the way the Prozor is processing the Optical signal.

It might have a rated 2V output, but if the Optical input and the PCM decoding is killing the level then it won't be generating enough signal to drive the Technics amp sufficiently.

Look, we're not taking about DACs at several hundreds of Pounds here. The Prozor and the other DAC are a few tens of Pounds. Why don't you try that Bluetooth DAC? Buy it through Amazon, and if it's pants, send it back. This story has taken up a lot of your time for something that's the cost of a Saturday night takeaway.