joe, you're correct that the tube warmth adjustment led's don't work w/o the tube. but, as the tube is in the adc circuit, these lights are meaningless when used as a dac only... folks have thought a possible reason why the unit may sound better w/the tube, is that it draws power away from the diodes in the adc circuit, & these, being crap, may let some unwanted signals feed back into the dac side. one of the recommended mods is replacing *all* the diodes, both dac & adc, w/schottky's, which work much better... could be part of the rfi problem you're experiencing. i'd suggest moving the dac, & the cd-player in relation to the tuna, to see if this has any effects. also, may want to put ferrite magnets on the power cords & interconnects. also, are you using any gain attenuation? the di/o, being a pro-audio product, outputs a 7v signal, while 2v is more typical of home-audio gear... i recall you mentioning using an attenuator module, mebbe this also has something to do w/the rfi...
re: getting it to sync properly, it seems to be very sensitive to the digital cabling; believe it or not, i have had great success w/the $10 rat-shack 75 ohm cable. no sync problems at all w/my nad changer. but, i'm gonna try an apogee wyde-eye pro cable. (~$25 street-price) brianw sez it's the best, short of dropping $1200 on an fim digital cable... also, the digital input resistor is 100 ohms (pro audio, again?); i replaced it w/a 75 ohm resistor. you really need to do a few tweaks to the di/o, along w/hooking up that stancor. the thing, quite good stock, really responds to these simple mods.
doug s.