That's my current setup. I was using one of the older StartTech USB sound cards but started noticing some rather strong images in WSJT-x's waterfall. Switching to the UFO202 improved things a lot, but still it didn't fully cancel them.
That got me looking at HDSDR's "Input Channel Calibration for Rx" panel. I was attempting to reduce stronger signals on LSB from showing up in the USB. A good example is FT8 activity on 30m showing up in the USB on HDSDR when the RS-HFIQ is tuned and operating WSPR.
The feature in HDSDR works quite well! But, I didn't try adjusting it with the 10 kHz separation suggested by HDSDR nor have I tested it on Transmit. I need to try it using the StartTech USB sound card. I found this page to be useful:
https://sites.google.com/site/g4zfqradio/hdsdr-iq-balance
I'm curious if you're on a Pi running Quisk is there a similar feature for balancing I/Q?
Thanks!
--Al
WD4AH