Problem Encountered In DSIX

[xrcd24bit]

I had DIY a DSIX (Digital Signal Isolation Exciter) according the attached diagram except :

1. 1SS176 were replaced by MUR1100

2. 0.1 uF capacitor was used instead of the output transformer

I connected the DSIX between a Pioneer PD T-09 CD player and the Audio Alchemy DDE 3.0 DAC. The DSIX worked and there was improvement in the resolution.

On the second day I removed some of the components which did not belong to the DSIX circuit and tested it again. Problem then encountered. The signal locked LED of the DAC flashed and sound came out from the loudspeaker for half second and in the next half second the loudspeaker was silent.

So I checked the DSIX again and found nothing wrong. I reconnected the DSIX between the CD player and the DAC. The DAC could not lock the signal from the DSIX at all.

I tried the 74HC04. The DAC also could not lock the signal from the DSIX.

I also tried the DSIX with a Denon CD player. The coaxial output of this player DIY with the circuit shown in my next thread. This time the DAC could lock the signal from the DSIX.

I do not know what is happening. Is the waveform of the DSIX output have problem that cannot be accepted by a DAC under certain circumstance ? What can I do to solve this problem ?

[xrcd24bit]

Attached is the circuit of the optical to coaxial output of my Denon CD player. The DSIX only worked with this coaxial output.