AVR preamp out question

Thanks for all your responses. I did try it again and it works. The problem was that my "little 5687 tubed linestage" doesn't have much output gain so that I have to crank it almost 3/4 full throttle to match my AVR. But it sounds great.
I just bought a Rogue Stereo 90 Magnum from a fellow A'goner and it sounds to good I had the "upgrade bug. I bought a pair of AZ Hologram II speaker cables, a Shunyata Aries IC, and a Cardas Clear USB cord for my Macbook/Maverick DAC !. My system is slowly evoving nicely.
Thanks again!

System:
Macbook/Maverick DAC 1 / Cardas Clear USB
5687 Tube Line stage designed and built by Randy Fay ($350 EBAY.)
Sony DA30ES 5.1 AVR
Rogue Stereo 90 Magnum
Silverline SR12's Front
NHT 3 Center Channel Speaker
AR 18b Speakers Rear
Energy 10 Subwoofer
AZ Hologram II Cable
Shunyata Aries IC''
Soundsilver Trilogy IC
Art Audio 1c IC
AP Copper Oval

Progress not perfection......

I have a HK 7200 i use in 6 direct mode with the pre-outs to a forte 4a for 2 channel to merlin tsm and it works great-not sure what the problem would be.

Why? What are preamp-outputs good for if they will not output a signal?

Depends on the AVR. Harman-Kardon preamp-outs wouldn't allow you to do this, for example.

It should work and is commonly done. What AVR do you have and have you tried different inputs on the tube preamp?

Kal