I spoke to the designer and the 600ohms load input is in fact a transformer not set with a resister. So it would seem that this is a transformer coupled design. I tried a CAT ultimate Mk11 last night (100ohms output) and its very good, transparent, non fatiguing etc but I still don't get the extended bottom octaves. On Patricia Barber modern cool I can follow the Double bass line down to the point where I am missing the lower notes. I Still get the leading edges etc of these notes just not the meat ,depth and scale that I've heard before. The best I've had the bottom end so far is with my 75ohm output pre off my headphone amp. but its too noisy.
Can someone please suggest why their 600ohm matched impedance , tranformer coupled design, might work better than a using a lower impedance pre in a bridged model into the 600ohms as I am trying. I know that matched impedance delivers better power transfer lower reflections but that Bridging delivers better voltage transfer. Maybe I just cant get the differential high enough with the low 600ohm input ??
As you can see I've read enough just to confuse myself. maybe keeping and eye out for an Atmasphere pre is the way to go. It does appeal to me.
Thanks again.