I must have blown the DAC by inserting a car incorrectly at some point.
changed the DAC IC and its sounding GREAT!!
I have the balanced outputs going into a Tascam LA40 mk2 so I can listen to the outputs on monitors and I'm using an old Behringer 4 channel Ultra Pro DI rack for testing mixing lots of channels at the same time.
The idea is I actually use this box for PC TV Alexa and whatever rubbish I use at home to test long term stability. does it crash , over heat and all that ! so far so good.
I've set the main faders to mix from -inf dB to +16dB and the main output faders from -inf dB to +18dB