OPT Grounding / Crosstalk

[draperphoto]

I recently built a stereo SE EL34 amp. Driver stage is a common 6sn7 stage followed by a 6sn7 cathode follower. The output stage is fixed bias and coupled to Edcor GSXE 10 OPT using the 43% tap for g2. PSU is bridge rectified and CLCRC filtered. The problem I am having is with the grounding of the secondary of the OPT. If I ground the + terminal everything is OK with only a small amount of crosstalk between channels. If I ground the - terminal there is 100% crosstalk between both channels. If I remove the load from one channel the signal will actually appear at full strength on the other loaded channel. The same effect also occurs if neither side of the secondary is grounded. I need to fix this because I need to take feedback from the OPT secondary but the phase is wrong with the - terminal grounded. Thanks in advance. ............Andrew